A cement and concrete industry publication
NationalStructuralConcreteSpecification
for BuildingConstruction
Fourth edition ...
NSCS Standard Specification
2
A technical committee of CONSTRUCT, the Concrete Structures Group, prepared this specificatio...
i
Foreword
This fourth edition of the NationalStructuralConcreteSpecification (NSCS) has been completely
reviewed and revis...
ii
construction and environmental management. It is expected that standards for these issues will be
evolving throughout t...
iii
National Structural Concrete Specification
for Building Construction
Contents
Standard Specification
Section 1 Scope 1 ...
iv
8.5 Surface cracking 21 94
8.6 Surface finishes 21 95
Section 9 Precast concrete 22 100
9.1 General 22 100
9.2 Precast ...
NSCS Standard Specification 1: Scope
NSCS Standard v
National Structural Concrete Specification
for Building Construction
F...
NSCS Standard Specification
NSCS Standardvi
1: Scope
NSCS Standard 1
Section 1 Scope
The NSCS has the same scope as BS EN 13670 for Building Structures.
The NSCS is l...
NSCS Standard Specification
NSCS Standard2
Section 2 Bibliography
2.1 Standards
BS 4449: 2005 Steel for the reinforcement ...
3: Definitions
NSCS Standard 3
BS EN ISO 14001: 2004 Environmental management systems – Requirementswithguidancefor use.
B...
NSCS Standard Specification
NSCS Standard4
3.1.2 Documents
When given in respect of drawings, documents, or schemes called...
3: Definitions
NSCS Standard 5
3.4.7 As-built drawings
Drawings to indicate what was built.
3.4.8 Reinforcement schedules
...
NSCS Standard Specification
NSCS Standard6
Section 4 Execution management
4.1 General requirements
4.1.1 Standards
Executi...
4: Execution management
NSCS Standard 7
4.2.3.2 Availability
Copies of all documents required for the construction of the ...
NSCS Standard Specification
NSCS Standard8
4.3 Quality management
4.3.1 Execution class
The works are to be built in accor...
5: Falsework and formwork
NSCS Standard 9
Section 5 Falsework and formwork
5.1 Standards
Design and construction should be...
NSCS Standard Specification
NSCS Standard10
No ferrous metals shall be left in the concrete cover zone when formwork has b...
6: Reinforcement
NSCS Standard 11
maintain them in their correct locations and prevent damage while the concrete is being ...
NSCS Standard Specification
NSCS Standard12
6.1.2.3 Pre-assembled welded fabrications delivered to site
Only firms that hav...
6: Reinforcement
NSCS Standard 13
6.1.7 Fibre reinforcement
Unless fully described in NSCS Project Specification, details o...
NSCS Standard Specification
NSCS Standard14
Section 7 Prestressed concrete construction
Note: This section is for in-situ ...
7: Prestressed concrete construction
NSCS Standard 15
7.2.1.2 Strand
Strand shall comply with BS 5896. The grade and diame...
NSCS Standard Specification
NSCS Standard16
7.3.2 Vents
Vents shall be fixed at injection and exit points and, where tendon...
7: Prestressed concrete construction
NSCS Standard 17
materials and procedures as proposed for the Works. The trial shall ...
NSCS Standard Specification
NSCS Standard18
Serial numbers of gauges and jacks■
Tendon identification■
Theoretical extensi...
8: Concrete and concreting
NSCS Standard 19
Daily maximum and minimum atmospheric shade temperatures shall be recorded usi...
NSCS Standard Specification
NSCS Standard20
8.1.4 Plant – other concrete
For supplies of concrete from sources other than ...
8: Concrete and concreting
NSCS Standard 21
curing shall be agreed with the CA. Curing membranes shall be compatible with ...
NSCS Standard Specification
NSCS Standard22
Note: This type of finish can be seen at the CONSTRUCT regional reference panel...
9: Precast concrete
NSCS Standard 23
for each precast element shall be made by the manufacturer and kept available for ins...
NSCS Standard Specification
NSCS Standard24
until the precast components are incorporated into the structure, including de...
10: Geometric tolerances
NSCS Standard 25
The hierarchy of tolerance adopted in the NSCS is such that the tolerance of eac...
NSCS Standard Specification
NSCS Standard26
10.2.2 Level
Level of floors measured relative to the intended design level at ...
10: Geometric tolerances
NSCS Standard 27
10.4.1 Preset bolt prepared for adjustment
Dy, Dz Dy
Dz
Dp ■ Distance of centre ...
NSCS Standard Specification
NSCS Standard28
10.5.2 Verticality by storey of the structure
Inclination of a column or wall ...
10: Geometric tolerances
NSCS Standard 29
10.5.6 Distance between adjacent columns and walls
Distance between adjacent col...
NSCS Standard Specification
NSCS Standard30
10.6.4 Distance between adjacent beams
Distance between adjacent beams, measur...
10: Geometric tolerances
NSCS Standard 31
10.7 Section of elements
10.7.1 Cross-section dimension of elements
Applicable t...
NSCS Standard Specification
NSCS Standard32
10.8.3 Location of reinforcement and ducts in prestressed elements
h
y + D
■ A...
10: Geometric tolerances
NSCS Standard 33
10.10 Holes and fixings
10.10.1 Holes
Size and location of hole relative to desig...
NSCS Standard Specification
NSCS Standard34
l3
D3
Inclination of fixing■
Permitted deviation D3 = greater of
5 mm or l3/20...
National Structural Concrete Specification
for Building Construction
Fourth edition complying with BS EN 13670: 2009
NSCS P...
NSCS Project Specification36
NSCS
Foreword
The Specification that follows shows what is required in a Project Specification u...
NSCS Project Specification 37
Project Specification
NSCS Project Specification
i) The specification for the structure shall b...
NSCS Project Specification38
NSCS
Section P1 Information to be supplied TO the Constructor
P1.1 General information
P1.1.1 ...
Project Specification
NSCS Project Specification 39
P1.1.3 Construction planning requirements
Note: the information here is...
NSCS Project Specification40
NSCS
P1.2 Design
P1.2.1 General
The design has been carried out in accordance with BS EN 1990,...
Project Specification
NSCS Project Specification 41
P1.3 Drawings and calculations
Project values should be entered in the ...
NSCS Project Specification42
NSCS
P1.4 Execution management
P1.4.1 Execution Class
The following parts of the structure are...
Project Specification
NSCS Project Specification 43
P1.4.3 Approvals timing
The timings given in NSCS Standard Specification...
NSCS Project Specification44
NSCS
P1.4.6 As-built geometry
The overall concrete dimension shall be checked:
List of require...
Project Specification
NSCS Project Specification 45
P1.5.3 Other materials
Materials not permitted:
Materials requiring spe...
NSCS Project Specification46
NSCS
P1.8 Concrete
P1.8.1 Designated concrete
To be In accordance with BS 8500–2 and BS EN 206...
Project Specification
NSCS Project Specification 47
P1.8.2 Designed concrete
To be in accordance with BS 8500–2 and BS EN 2...
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National structural concrete_specification_for_building_construction

ational structural concrete_specification_for_building_construction
Published on: Mar 3, 2016
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Transcripts - National structural concrete_specification_for_building_construction

  • 1. A cement and concrete industry publication NationalStructuralConcreteSpecification for BuildingConstruction Fourth edition complying with BS EN 13670: 2009
  • 2. NSCS Standard Specification 2 A technical committee of CONSTRUCT, the Concrete Structures Group, prepared this specification as the 4th edition of National Structural Concrete SpecificationforBuildingConstruction, originally published in February 1998. Technical Committee Attending Members Julian Maw (Chairman) – CONSTRUCT Paul Toplis (Technical Editor) – Price & Myers Edwin Bergbaum – Waterman Structures Ltd Gordon Clark – Gifford Andrew Cotter – MPA/The Concrete Centre Alistair Craig – Carillon Building Neil Crook – The Concrete Society Roger Davies – Gifford Richard Day – The Concrete Society James Fudge – British Precast Charles Goodchild – MPA/The Concrete Centre Patrick Hallinan – Mace Graham Hardwick – John Doyle Construction Roger Hewitt – Scott Wilson Ltd Mike Howard – Laing O’Rourke Deborah Lazarus – Arup/Institution of Structural Engineers Neil Loudon – Highways Agency John Webster – BAA Airports Ltd Rob Westcott – Alan Baxter & Associates Visiting Specialists Kevin Bennett – Freyssinet Ltd. Richard Digman – UK CARES Corresponding Members Rod McClelland – CBDG Brian Spencer – Southern Water Past Members Clive Budge, Andy Butler, Peter Goring, John Mason CONSTRUCT and the authors thank the numerous organisations from all sections of the industry whose views and comments have been sought and carefully reviewed for inclusion. The work of preparing this specification was managed and funded by CONSTRUCT and MPA – The Concrete Centre. All data, information and opinions contained herein aim to reflect accepted practices at the time of publication. While every effort has been made to ensure accuracy, no responsibility can be accepted for errors and omissions, however caused. No responsibility for any loss occasioned as a result of material in the publication is accepted by the authors or publishers. Responsibility for interpretation of the material contained in this publication rests entirely with the user. All rights reserved. No part of this publication may be reproduced, stored in a retrievals system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of CONSTRUCT, except as noted. Production editor: Gillian Bond, Words & Pages, Hythe, CT21 5LS Printed by Michael Burbridge Ltd, Maidenhead, UK. CCIP-050 First edition published February 1998 This 4th edition published April 2010 ISBN 978-1-904818-96-0 Price Group P © CONSTRUCT 2010 Published by The Concrete Centre, part of the Mineral Products Association Riverside House 4 Meadows Business Park Station Approach, Blackwater, Camberley, Surrey GU17 9AB Tel: +44 (0)1276 606800 Fax: +44 (0)1276 606801 www.concretecentre.com Prepared by CONSTRUCT Riverside House 4 Meadows Business Park Station Approach, Blackwater, Camberley, Surrey GU17 9AB Tel: +44 (0)1276 38444 Fax: +44 (0)1276 38899 www.construct.org.uk Front cover image courtesy of The Concrete Centre. © Grant Smith Photography
  • 3. i Foreword This fourth edition of the NationalStructuralConcreteSpecification (NSCS) has been completely reviewed and revised to encompass the requirements of the Eurocodes and BS EN 13670: 2009, Executionofconcretestructures. It provides a BS EN 13670-compliant specification for use in structural concrete building construction designed to the Eurocodes. The adoption in the UK for the first time of a workmanship or execution standard in place of the workmanship requirements forming part of a design standard has necessitated some changes to the structure of this document and terminology, but this edition of the NSCS still has the same objective, that is to provide a definitive, simple and straightforward specification without unnecessary constraints. The section on execution management follows the introduction of this term in BS EN 13670 and the numbering of the specification sections follows that of the standard. BS EN 13670 requires the use of an execution specification, consisting of documents and drawings to communicate additional and project-specific construction requirements between Client, Designer and Constructor. The NSCS for Building Construction forms part of the Execution Specification, called for in BS EN 13670: 2009, and has been designated by its National Annex as Non-Contradictory Complementary Information. The tolerance requirements of BS EN 13670 have been drawn up solely to assure structural safety of the building structure for a Eurocode design and are therefore not always sufficient to ensure reasonable construction coordination with following trades. The NSCS tolerances provide additional requirements aimed at coordination for normal circumstances and confirm the responsibility of different parties for ensuring the issues are carefully considered, where required, to suit the details of a particular project. The NSCS contains three documents: the NSCS Standard Specification and NSCS Project Specification (which together form the BS EN 13670 Project Specification) and NSCS Guidance. The latter provides informative guidance for interpretation and usage of both Specifications. Clauses in BS EN 13670 have been repeated at times for clarity. The NSCS Standard Specification gives standards and technical data for use in the UK. The interrelationship of this Specification with BS EN 13670 and the contract documents is illustrated in Figure A. The NSCS Guidance to execution management describes how NSCS Standard Specification, a completed NSCS Project Specification, the drawings and other documents taken together provide all the information required to be included in the Execution Specification of BS EN 13670. The functions of each part are summarised below. The NSCS Standard Specification provides a base Specification with standard clauses on execution, materials and construction for the production of consistent and well-constructed reinforced concrete building structures. The NSCS Project Specification provides the information and requirements specific to the project. It records, by exception, any amendments to the Standard Specification considered necessary by the designer and is the part of the Specification where information is provided by the tenderer. This enables tender documents or the contract for construction to consist of a Project Specification only, because it refers explicitly to the Standard Specification as its base document. To aid the task of preparing a Project Specification, permission is hereby expressly given for users of this document to copy the whole of Project Specification without infringement of copyright. A data disc, or download, is available from CONSTRUCT to enable easy electronic completion and distribution of the Project Specification. To aid the task the NSCS Project Specification has prompts to encourage specifications requiring best practice in sustainable
  • 4. ii construction and environmental management. It is expected that standards for these issues will be evolving throughout the construction industry over the next few years and so specifiers should be adding their requirements on most projects. The NSCS Guidance is a companion document to the specification and gives background information together with explanations of why certain clauses have been adopted. The information is intended to be of use to both the Designer and Constructor. The Guidance does not form part of the Execution Specification. The NSCS assumes the Engineer remains responsible for using reasonable skill, care and diligence to design the structure and that the Constructor builds what is shown on the drawings to the specified standard. The Constructor is expected to exercise in the performance of his duties all such skill, care and diligence as may be expected of an experienced and competent Constructor used to working on projects of similar size, scope and complexity of structural concrete works using appropriately qualified and experienced staff. Prescriptive restraints have been avoided, so enabling the Constructor’s experience to be used for efficient construction. The NSCS aims to ensure that the specification draws together all the day-to-day information needed by the Designers, Contract Administrator (CA) and the Constructor; it therefore includes information which may duplicate provisions in project preliminaries. It is important that, when the NSCS Standard Specification is used, all the project team make use of it and should the project preliminaries differ, the NSCS Project Specification should indicate the required changes. The benefits of using NSCS will best be achieved by continuing the collaboration between Contractors, Specifiers and Designers that arose during its development. NSCS provides for agreement to be reached between the Constructor and the Designer on project-specific items that affect the pricing of the works. A review panel will keep the document up to date in the light of comments and feedback received from all parts of the industry. Any inaccuracies and ambiguities found or proposals for future editions should be submitted to CONSTRUCT at enquiries@construct.org.uk Figure A The NSCS in context Project contract documents Concrete construction package, Execution specification Project packages, Concrete project package Drawings, Schedules, Building regulations, Statutory requirements NSCS Project Specification NSCS Standard Specification BS EN 13670
  • 5. iii National Structural Concrete Specification for Building Construction Contents Standard Specification Section 1 Scope 1 57 Section 2 Bibliography 2 119 2.1 Standards 2 119 2.2 General 3 121 Section 3 Definitions 3 57 3.1 Agreement, acceptance 3 57 3.2 Contract administrator (CA) 4 57 3.3 Design calculations 4 57 3.4 Drawings and schedules 4 57 3.5 Employer 5 58 3.6 Engineer 5 59 3.7 Manufacturer 5 59 3.8 Project specification 5 59 3.9 Prestressed concrete 5 59 3.10 Reference panels 5 59 3.11 Site 5 59 3.12 Spacers 5 59 3.13 Temporary works coordinator 5 59 Section 4 Execution management 6 59 4.1 General requirements 6 63 4.2 Documentation 6 64 4.3 Quality management 8 66 Section 5 Falsework and formwork 9 68 5.1 Standards 9 68 5.2 Materials 9 68 5.3 Release agents 9 69 5.4 Formwork use 9 70 5.5 Block outs and cast-in items 9 71 5.6 Formwork ties 9 71 5.7 Loading, striking and backpropping 10 72 5.8 Construction joints and pour sizes 10 72 5.9 Water-resisting construction 10 73 Section 6 Reinforcement 11 74 6.1 Materials 11 74 6.2 Execution 13 77 Section 7 Prestressed concrete construction 14 78 7.1 Design and quality control 14 78 7.2 Materials 14 79 7.3 Execution 15 80 7.4 Records 17 82 Section 8 Concrete and concreting 18 82 8.1 Concrete 18 82 8.2 Concreting 20 91 8.3 Curing 20 92 8.4 Inspection – post-concreting 21 94 Standard Specification Guidance Notes
  • 6. iv 8.5 Surface cracking 21 94 8.6 Surface finishes 21 95 Section 9 Precast concrete 22 100 9.1 General 22 100 9.2 Precast concrete products 23 101 9.3 Precast concrete elements 23 101 9.4 Handling and storage 23 101 9.5 Placing and adjustment 24 101 9.6 Jointing 24 101 Section 10 Geometric tolerances 24 102 10.1 General 24 102 10.2 Overall structure 25 104 10.3 Base support (foundations) 26 106 10.4 Foundation bolts and similar inserts 26 106 10.5 Elements – columns and walls 27 106 10.6 Elements – beams and slabs 29 107 10.7 Section of elements 31 107 10.8 Position of reinforcement within elements 31 108 10.9 Surface straightness 32 109 10.10 Holes and fixings 33 109 10.11 Staircases 34 110 10.12 Precast concrete elements 34 110 Project Specification Section P1 Information to be supplied TO the Constructor 38 111 P1.1 General information 38 111 P1.2 Design 40 112 P1.3 Drawings and calculations 41 112 P1.4 Execution management 42 114 P1.5 Materials 44 115 P1.6 Project requirements 45 116 P1.7 Water-resisting construction 45 117 P1.8 Concrete 46 117 P1.9 Surface finishes 50 117 P1.10 Precast concrete 51 117 P1.11 Prestressed concrete construction 51 118 P1.12 Deflection allowances 52 118 P1.13 Further information 52 118 Section P2 Information to be supplied BY the Constructor 52 119 P2.1 General information 52 119 P2.2 Design 53 119 P2.3 Drawings and calculations 53 119 P2.4 Execution management 53 119 P2.5 Materials 53 119 P2.6 Project requirements 54 119 P2.7 Water-resisting construction 54 119 P2.8 Concrete and concreting 54 119 P2.9 Further information 54 119 Standard Specification Guidance Notes
  • 7. NSCS Standard Specification 1: Scope NSCS Standard v National Structural Concrete Specification for Building Construction Fourth edition complying with BS EN 13670: 2009 Standard Specification
  • 8. NSCS Standard Specification NSCS Standardvi
  • 9. 1: Scope NSCS Standard 1 Section 1 Scope The NSCS has the same scope as BS EN 13670 for Building Structures. The NSCS is laid out in terms of processes, and it uses the same sequence as BS EN 13670. European and British Standards are referenced rather than reproduced within the document. The NSCS covers requirements for the construction of concrete building structures of in-situ concrete, precast concrete, and hybrid concrete systems. It is intended for use with structures designed to BS EN 1992, although it can be used when other design standards are used. Where the NSCS is to be used for structures in extreme environments, those produced by specialist construction techniques or those of a specialist design nature, the Project Specification should include the particular requirements where appropriate. It is expected that the requirements for concrete in more specialist geotechnical works will be covered by a specification such as the ICE Specificationfor pilingand embedded retaining walls (SPERW). The NSCS should be coordinated where required with other project specifications such as the SPERW. The NSCS is written with safety in mind but does not specify Health and Safety requirements as they are legal regulations that apply to all construction and are inherent within this specification. Where specifications, standards or regulations are referred to they shall refer to the latest editions unless reference is made to a specific dated clause in a standard. Specific obligations are placed on the Constructor, the Employer and the Engineer. In some cases these will be different organisations; sometimes any or all will be represented by the same organisation. However, their responsibilities remain as required under the Contract. The NSCS Project Specification is to be read in conjunction with this Standard Specification and outlines project information specific to a particular project that is additional to the requirements of Standard Specification. The NSCS Project Specification covers the exchange of information necessary between the Employer and Constructor at tender stage and contract stage. Completion of the Project Specification is intended to be as required for the stage for which it is being used, i.e. at time of tender or contract commencement. The NSCS Project Specification allows the Engineer responsible for the design the freedom to incorporate specific clauses to vary and add to the Standard Specification clauses. It is emphasised that the Standard Specification has been produced as a non-prescriptive specification to meet the standards required by BS EN 13670 and therefore any amendments through the Project Specification should be as few as possible. The pro-forma layout of NSCS Project Specification acts as an aide memoire to the disclosure of relevant information for most types of project. NSCS Guidance provides background information on the content and explains why certain clauses have been adopted. NSCS Guidance is designed to be ‘dipped into’, and read with the relevant clause in Standard and Project Specification; as a result there is some intentional duplication.
  • 10. NSCS Standard Specification NSCS Standard2 Section 2 Bibliography 2.1 Standards BS 4449: 2005 Steel for the reinforcement of concrete – Weldable reinforcing steel – Bar, coil and decoiled product – Specification. BS 4483: 2005 Steel fabric for the reinforcement of concrete – Specification. BS 4486: 1980 Specification for hot rolled and hot rolled and processed high tensile alloy steel bars for the prestressing of concrete. BS 5896: 1980 Specification for high tensile steel wire and strand for the prestressing of concrete. BS 5975: 2008 Code of practice for temporary works procedures and the permissible stress design of falsework (incorporating corrigendum No. 1). BS 7973-1: 2001 Spacers and chairs for steel reinforcement and their specification – Product performance requirements. BS 8102: 2009 Code of practice for protection of structures against water from the ground. BS 8500-1: 2006 Concrete – Complementary British Standard to BS EN 206-1 – Part 1: Method of specifying and guidance for the specifier. BS 8500-2: 2006 Concrete – Complementary British Standard to BS EN 206-1 – Part 2: Specification for constituent materials and concrete. BS 8666: 2005 Scheduling, dimensioning, bending and cutting of steel reinforcement for concrete – Specification (incorporating amendment No. 1). BS EN 197-1: 2000 Cement – Compositions, specifications and conformity criteria for common cements. BS EN 206-1: 2000 Concrete – Specification, performance, production and conformity. BS EN 287-1: 2004 Qualification test of welders – Fusion welding – Steels (AMD Corrigendum 15578) (AMD 16275) (AMD Corrigendum 16831). BS EN 446: 2007 Grout for prestressing tendons – Grouting procedures. BS EN 447: 2007 Grout for prestressing tendons – Basic requirements. BS EN 1011-2: 2001 Welding. Recommendations for welding of metallic materials – Arc welding of ferritic steels (AMD 14926). BS EN 1090-2: 2008 Execution of steel structures and aluminium structures – Technical requirements for the execution of steel structures. BS EN 1990: 2002 Eurocode – Basis of structural design. BS EN 1991 Eurocode 1 – Actions on structures (10 parts). BSI, 2002–2006. BS EN 1992 Eurocode 2 – Design of concrete structures (3 parts). BSI, 2004–2006. BS EN 12350: 2009 Testing fresh concrete (7 parts). BS EN 12390: 2009 Testing hardened concrete (8 parts). BS EN 12812: 2004 Falsework – Performance requirements and general design. BS EN 13139: 2002 Aggregates for mortar. BS EN 13369: 2004 Common rules for precast concrete products. BS EN 13391: 2004 Mechanical tests for post-tensioning systems. BS EN 13670: 2009 Execution of concrete structures, and National Annex to BS EN 13670. BS EN ISO 4157: 1999 Construction drawings – Designation systems (3 parts). BS EN ISO 9000: 2005 Quality management systems – Fundamentals and vocabulary. BS EN ISO 9001: 2008 Quality management systems – Requirements (incorporating corrigendum July 2007).
  • 11. 3: Definitions NSCS Standard 3 BS EN ISO 14001: 2004 Environmental management systems – Requirementswithguidancefor use. BS EN ISO 15614 Specification and qualification of welding procedures for metallic materials – Welding procedure test. (13 parts). BSI, 2002–2008. BS EN ISO/IEC 17025: 2005 General requirements for the competence of testing and calibration laboratories (AMD corrigendum 16767). BS OHSAS 18001:2007 Occupational health and safety management systems. 2.2 General BAMFORTH, P. B. Early-age thermal crack control in concrete, C660. CIRIA, 2007. CARES and European Technical Approvals: CARES Post-tensioning systems, Part 2 – The supply and/or installation of post-tensioning systems. November 2007. CARES Post-tensioning systems, Part 9 – CARES Registration scheme for post- tensioning operatives. November 2007. CARES Steel for reinforced concrete, Appendix 6 – Quality and operations assessment schedule for the tack welding of reinforcing steel. January 2006. CARES Steel for reinforced concrete, Appendix 10 – Quality and operations assessment schedule for pre-assembled welded fabrications using welded semi-structural and/or structural joints. January 2006. EOTA. ETAG 013 Guideline for European Technical Approval of post-tensioning kits for prestressing of structures. Brussels, EOTA, 2002. fib. Corrugated plastic ducts for internal bonded post-tensioning, fib Bulletin 7. fib, 2000. HARRISON, T. A. Formworkstrikingtimes–criteria,predictionandmethodofassessment, R136. CIRIA, 1995. ICE. ICE Specification for piling and embedded retaining walls, 2nd edition. Thomas Telford, 2007. INSTITUTION OF STRUCTURAL ENGINEERS. Standard method of detailing structural concrete. A manual for best practice, 3rd edition. IStructE, 2006. PALLET, P F. Guide to flat slab falsework and formwork, CS140. The Concrete Society, on behalf of CONSTRUCT, 2003. THE CONCRETE SOCIETY. Formwork – A guide to good practice, CS030, 2nd edition. The Concrete Society, 1995. THE CONCRETE SOCIETY. Post-tensioned concrete floors –Design handbook, TR43, 2nd edition. The Concrete Society, 2004. Section 3 Definitions The following definitions, in addition to those given in BS EN 13670: 2009, apply for the purpose of this Specification. 3.1 Agreement, acceptance When by or of the CA, agreement or acceptance shall have the following limitations. 3.1.1 Samples When given in respect of samples of materials, execution or proposals for methods of construction submitted in accordance with this Specification, shall not be interpreted as denoting any degree of satisfaction with the materials used in, or the execution of the Works.
  • 12. NSCS Standard Specification NSCS Standard4 3.1.2 Documents When given in respect of drawings, documents, or schemes called for by the Specification or proposed by the Constructor, is only for conformity with the design concept and design information given in the Contract Documents or contained in subsequent instructions from the CA. Acceptance or agreement shall not diminish or relieve the obligations of the Constructor under the Contract. 3.2 Contract Administrator (CA) The named individual or company, engaged to act for and on behalf of the Employer for the purpose of accepting proposals from the Constructor, issuing technical information to the Constructor and monitoring the work of the Constructor. 3.3 Design calculations The calculations produced generally by the Engineer. For some specialist work they may be produced by the Constructor. 3.4 Drawings and schedules 3.4.1 General arrangement drawings (GAs) Plans and sections indicating the layout and dimensions of each floor of the Works. The drawings will be in sufficient detail to allow the formwork to be constructed and will show or reference all inserts or cast- in items and holes. Drawings should indicate the locations of concrete grades and finishes. 3.4.2 Design information drawings Drawings prepared to show the design information required to enable reinforcement detail drawings to be produced. 3.4.3 Specialist drawings – prestressed concrete Fully dimensioned drawings, plans and cross-sections of tendons and anchorage layouts indicating tendon profiles at regular intervals along each length, support details, stressing sequences etc. Stressing end, dead end anchorages, and any ordinary reinforcement sizes and locations required to supplement the post-tensioning design and bursting reinforcement at anchorages to suit anchor type and layout, shall be clearly defined. 3.4.4 Reinforcement detail drawings Drawings prepared to show the layout of the various types of reinforcement used in the construction of the Works. They shall be prepared in accordance with the requirements of BS EN 1992 and the Standard method of detailing structural concrete – A manual for best practice (IStructE). 3.4.5 Builders’ work drawings Drawings prepared to show coordinated builders’ work – holes, cast-in services and fixings, etc. 3.4.6 Temporary works and erection drawings Drawings prepared to show necessary falsework, formwork and propping that are employed to construct the Works in a safe manner.
  • 13. 3: Definitions NSCS Standard 5 3.4.7 As-built drawings Drawings to indicate what was built. 3.4.8 Reinforcement schedules Schedules prepared to show the details of each bar to be cast into the concrete. They shall be prepared in accordance with BS 8666 3.4.9 Construction sequence information Drawings, sketches or other information, prepared by the CA, indicating any special requirements or methods, which the Constructor must consider in the preparation of their temporary works in order to erect the Works in a safe manner. 3.5 Employer The individual or company placing the contract with the Constructor. 3.6 Engineer The individual or organisation responsible for the overall design of the Structure. 3.7 Manufacturer For precast concrete proprietary products the manufacturer is the individual or organisation responsible for the design of the precast proprietary products. 3.8 Project specification National structural concrete specification for building construction – NSCS Standard Specification and NSCS Project Specification. 3.9 Prestressed concrete Concrete that is subjected to pre-tensioning or post-tensioning. 3.10 Reference panels Full size concrete panels of Plain and Ordinary formed finishes located regionally by CONSTRUCT. 3.11 Site The designated place where the Constructor will construct the Works. 3.12 Spacers All chairs, blocks, supports and devices of a special nature required to hold the reinforcement in the correct position during concreting. 3.13 Temporary Works Coordinator The named individual employed by the Constructor responsible for coordinating the temporary works for construction of the works.
  • 14. NSCS Standard Specification NSCS Standard6 Section 4 Execution management 4.1 General requirements 4.1.1 Standards Execution shall be in accordance with BS EN 13670 as supplemented by the Project Specification and all statutory requirements. Where there is a difference between the requirements of BS EN 13670 and the Project Specification, the Project Specification takes precedence. 4.1.2 Materials 4.1.2.1 General All materials used in the structure shall comply with the Project Specification and current versions of standards referred to therein. The CA may specify samples for testing and the Constructor shall arrange for such samples to be supplied, identified, stored and tested and the results delivered to the CA in accordance with the relevant standards and the Project Specification requirements. 4.1.2.2 Proprietary products and materials These shall be used in accordance with the manufacturer’s written instructions and relevant European Product Standards where available. 4.1.2.3 Third-party inspections Allow reasonable access to the site for technical inspection by third parties at all times. 4.1.2.4 Water-resisting construction Where water-resisting construction is specified, submit to the CA for agreement: details of the materials used and the execution, which are to be in accordance with BS 8102; and written confirmation from the supplier of the water-resisting materials that they will not be adversely affected by the proposed environment, concrete, curing and release agents, placing methods, joints, finishes, reinforcement and its support details, or loads. 4.2 Documentation 4.2.1 Quality plan Operate an agreed quality management system to BS EN ISO 9000 unless otherwise agreed with the CA. The system shall be accessible for audit. If it is agreed that a quality management system to BS EN ISO 9000 is not required the Constructor shall prepare a quality plan for the project. The Quality Plan shall be given to the CA for acceptance at least five working days before the works start. 4.2.2 Execution documentation Produce the documents as required and provide one copy to the CA at the time stated in the NSCS Project Specification or no later than five working days after each is prepared. 4.2.3 Information coordination and availability 4.2.3.1 NSCS Project Specification When NSCS Project Specification is revised all changes must be clearly identified.
  • 15. 4: Execution management NSCS Standard 7 4.2.3.2 Availability Copies of all documents required for the construction of the structure, including all inspection reports, shall be available for review on site during the contract period. 4.2.3.3 Coordination The Constructor shall ensure that the coordinated information they prepare (as required by the NSCS Project Specification Cl. P1.3, P1.4, P1.8, P1.10 & P1.11 and Section P2) is submitted to the CA for agreement in accordance with the requirements of NSCS Project Specification Tables P1.3 & P1.4.2. 4.2.4 Drawings and reinforcement schedules 4.2.4.1 Standards To be in accordance with BS EN ISO 4157. Revisions, with the date made, and status shall be clearly shown. A circle or cloud around drawing revisions should identify the changes made for the latest revision symbol. The changes should be described in notes on the drawing corresponding to the latest revision symbol. 4.2.4.2 Register The Constructor shall maintain a register of all drawings they receive and issue, identifying the source of the drawing, revision symbol and date received or issued by the Constructor. 4.2.4.3 Production Drawings are to be produced as detailed in NSCS Project Specification Table P1.3. Where the drawings are to be prepared by a manufacturer of precast concrete products, or a specialist post- tensioning contractor, the Constructor is to ensure that the drawings are issued to the CA in accordance with the requirements of NSCS Project Specification Table P1.3. 4.2.4.4 Circulation The method of circulation, number of drawings to be issued and dates for issue of drawings shall be in accordance with NSCS Project Specification Table P1.3, agreed with the CA and recorded in the quality plan. 4.2.4.5 Reinforcement schedules The Constructor shall be responsible for the accuracy of any schedules that they produce. 4.2.4.6 As-built drawings The Constructor shall provide sufficient information to the CA to allow coordination of the production of as-built drawings, where these are to be produced by the CA. 4.2.4.7 Builders’ work drawings Where the Constructor is to produce coordinated builders’ work drawings the CA shall provide the required information in accordance with an agreed programme. 4.2.5 Construction planning – temporary works The CA’s construction sequence information must be considered in the preparation of the Constructors’ temporary works drawings showing all stability requirements during erection. Method statements for erection and dismantling of temporary works including all details of propping/ repropping and backpropping through the structure are to be prepared by the Constructor and agreed with the CA.
  • 16. NSCS Standard Specification NSCS Standard8 4.3 Quality management 4.3.1 Execution class The works are to be built in accordance with Execution Class 2, other than for post-tensioned construction where Class 3 is to be used, unless otherwise specified in NSCS Project Specification. 4.3.2 Setting out Set out the structure to the given setting out information. 4.3.3 Inspection In addition to the Constructor’s inspection of the materials and execution in accordance with BS EN 13670 the Constructor is to give reasonable notice, as given in NSCS Project Specification, to allow inspection by the CA at the following stages: Before each concrete pour.■ Before prestressing work starts.■ Before covering up or backfilling.■ For water-resisting construction to allow inspection jointly with Constructor as Cl. 8.4.2 of this■ Specification. 4.3.4 Modifications Obtain the written agreement of the CA to any modifications of this Specification before any work is started. 4.3.5 Storage All materials shall be stored in an agreed manner that prevents damage or degradation and is in accordance with all manufacturers’ requirements. 4.3.6 Acceptance procedure The CA shall comment on all information supplied within five working days of receipt. Acceptance or agreement by the CA shall have no effect unless given in writing. 4.3.7 Testing Supply three copies of all test reports to the CA as soon as they are available. 4.3.8 Action in the event of a non-conformity Any test or inspection reports that show that any part of the structure does not meet the specified■ criteria shall be reported to the CA, as soon as the results are available. Provide proposals for dealing with the non-conformity to the CA within five working days of■ reporting the results. A course of action shall be agreed within a further five working days.■ The cost of all additional testing and remedial works shall be at the Constructor’s expense.
  • 17. 5: Falsework and formwork NSCS Standard 9 Section 5 Falsework and formwork 5.1 Standards Design and construction should be in accordance with the following where applicable: BS 5975:■ Code of practice for temporary works procedures and the permissible stress design of falsework Formwork: a guide to good practice■ (Concrete Society Publication) CS030 ■ Guide to flat slab falsework and formwork CS140 (Pallet, 2003, Concrete Society publication on behalf of CONSTRUCT) CIRIA Report 136■ Formwork striking times – Criteria, prediction and method of assessment (Harrison, 1995) BS EN 1990 & BS EN 1991■ BS EN 12812■ 5.2 Materials Permanent formwork may be used subject to the agreement of the CA. New timber and wood products should all be certified as legally sourced by CPET (The Central Point of Expertise on Timber) recognised schemes. 5.3 Release agents Release agents shall be chosen to suit the method of construction and the finish required, and shall take note of the requirements of following trades. They shall not be adversely affected by the weather. 5.4 Formwork use 5.4.1 Ground support Concrete shall not be cast directly against existing construction or faces of excavations without prior agreement of the CA. Where structural concrete relies on permanent or temporary support from the ground, ensure that the support is firm enough for concreting operations. 5.4.2 Cleanliness Formwork shall be clear of all debris, water, snow and ice before concrete is placed. 5.5 Block outs and cast-in items Set out and fix all cast-in items shown or referenced on the drawings. Any clashes between holes, cast in items and reinforcement shall be resolved to the agreement of the CA before any concrete is placed. Block out items shall be cleared out after concreting. 5.6 Formwork ties Through ties may be used to support vertical faces of formwork other than in water-resisting construction or as agreed with the CA.
  • 18. NSCS Standard Specification NSCS Standard10 No ferrous metals shall be left in the concrete cover zone when formwork has been struck. Any holes left exposed to view in the faces of the concrete shall be filled to the agreement of the CA. 5.7 Loading, striking and backpropping 5.7.1 Temporary construction loads Ensure the structure is not subjected to temporary loads during construction that will cause distress, taking account of the maturity of the concrete at the time of loading. 5.7.2 Striking Falsework and formwork shall be struck at a time determined by the Constructor to comply with this Specification. Formwork shall be removed carefully so as to avoid damage to the concrete surface. 5.7.3 Backpropping The exact sequence of propping/repropping and backpropping through the structure, set out in a method statement by the Constructor, shall be agreed with the CA in advance, and should have no damaging effect on the Permanent Works 5.7.4 Cold weather concreting Any special requirements for the formwork design, including any use of heated forms or changes in design formwork pressure for concreting in cold weather, shall be agreed with the CA in advance. 5.8 Construction joints and pour sizes 5.8.1 Geometry Produce drawings showing the layout of construction joints and agree their location with the CA. Joints are to be positioned so as not to cause the structure any distress. Pour sizes for different types of construction, except as agreed otherwise with the CA, shall be as shown below. Construction Maximum area (m2 ) Maximum dimension (m) Water-resisting walls 25 5 Water-resisting slabs 100 10 Slabs with major restraint at both ends 100 13 Slabs with major restraint at one end only 250 20 Slabs with little restraint in any direction 500 30 Walls 40 10 5.8.2 Joint preparation Carefully prepare construction joint surfaces to expose the coarse aggregate to provide a key by a method to be agreed with the CA. 5.9 Water-resisting construction 5.9.1 Waterstops Use waterstops in all construction joints and movement joints in accordance with the manufacturer’s written instructions. Obtain the agreement of the CA for the methods to be used to
  • 19. 6: Reinforcement NSCS Standard 11 maintain them in their correct locations and prevent damage while the concrete is being placed and during or after removal of the Formwork. Submit for agreement with the CA drawings indicating the positions of joints and details of waterstops to be used. Details shall include schedules of all junction pieces, which shall be purpose made, and isometric layouts of waterstops. Where centre section waterstops are proposed submit to the CA for agreement the methods to be used to ensure full compaction of the concrete around the waterstop. 5.9.2 Formwork ties Methods of fixing formwork that result in holes through the concrete section when formwork is removed shall not be used, unless agreed with the CA. Formwork ties used shall be of a type to maintain water resistance of the construction. Section 6 Reinforcement 6.1 Materials 6.1.1 General 6.1.1.1 Standards All reinforcement shall comply with the requirements of BS 4449, BS 4483, and BS 8666 as appropriate. Reinforcement in accordance with BS 4449 shall be Grade 500 unless otherwise specified in NSCS Project Specification. 6.1.1.2 Certification – supplier Unless otherwise agreed by the CA, all reinforcement suppliers shall hold a valid Certificate of Approval for manufacture and/or fabrication issued by the UK Certification Authority for Reinforcing Steel (CARES), or equivalent. A supplier Certificate of Approval Reference shall be stated on all documentation. 6.1.1.3 Certification – cutting and bending If reinforcing steel is cut and bent by other than a CARES-approved supplier, the fabricator shall operate a quality management system to BS EN ISO 9001, which shall be approved as part of the Constructor’s quality management system and comply with BS 8666. 6.1.2 Reinforcement handling 6.1.2.1 Storage All reinforcement shall be delivered in properly identifiable tagged bundles, mats or prefabricated assembly and shall be stored on site in a manner so as not to become contaminated by deleterious materials or otherwise damaged; fabric shall be stored flat. 6.1.2.2 Handling Reinforcement shall not be dropped from height, mechanically damaged or shock loaded in any way.
  • 20. NSCS Standard Specification NSCS Standard12 6.1.2.3 Pre-assembled welded fabrications delivered to site Only firms that have achieved certification to CARES SRC Appendix 10 – Quality and operations assessment schedule for the manufacture of pre-assembled welded fabrications using welded semi- structural and/or structural joints, or equivalent, shall be permitted to supply pre-assembled welded fabrications. Only firms that have achieved certification to CARES SRC Appendix 6 – Quality and operations assessment schedule for the tack welding of reinforcing steel, or equivalent, shall be permitted to bid for or undertake contracts to supply pre-assembled tack-welded fabrications. 6.1.3 Spacers 6.1.3.1 General Supply, detail and fix all spacers. The materials and workmanship shall be in accordance with BS 7973: Spacers and chairs for steel reinforcement and their specification – Product performance requirements. Ensure that the spacers have the required performance characteristics. 6.1.3.2 Exposed finishes In exposed finish work the type of spacer used shall be agreed with the CA before any work is started. 6.1.4 Continuity strips 6.1.4.1 Supply Proprietary continuity strips can be used subject to agreement by the CA. 6.1.4.2 Quality All continuity strip manufacturers shall hold a valid CARES Technical Approval certificate or equivalent, unless otherwise agreed by the CA. 6.1.5 Couplers 6.1.5.1 Supply Details of the source and suppliers shall be forwarded to the CA for agreement. 6.1.5.2 Quality All coupler manufacturers shall have a valid Technical Approval certificate issued by CARES, or equivalent, unless agreed otherwise by the CA. All coupler suppliers shall have a valid Technical Approval certificate issued by CARES, or equivalent, for the application of couplers, unless agreed otherwise by the CA. Reinforcing bars shall be adequately and appropriately prepared by the supplier to receive the agreed couplers. 6.1.6 Punching shear reinforcement systems 6.1.6.1 Supply Details of the source and suppliers shall be forwarded to the CA for agreement. 6.1.6.2 Quality All punching shear reinforcement system manufacturers shall hold a valid Technical Approval certificate issued by CARES, or equivalent, unless otherwise agreed by the CA.
  • 21. 6: Reinforcement NSCS Standard 13 6.1.7 Fibre reinforcement Unless fully described in NSCS Project Specification, details of the proposed fibres, dosage, source and suppliers shall be forwarded to the CA for agreement. 6.2 Execution 6.2.1 General All reinforcement shall be fixed in position in accordance with the reinforcement detail drawings and reinforcement schedules. Any alterations of reinforcement shall be carried out only with the prior written agreement of the CA. 6.2.2 Tying All tying of reinforcement shall be carried out with black annealed mild steel 16 gauge tying wire, unless agreed otherwise with the CA. All ends shall be bent away from the concrete face and all loose ends shall be removed prior to placing the concrete. 6.2.3 Welding 6.2.3.1 General The location of all welded joints shall be agreed the CA. Tack welding on site will not be permitted, unless agreed with the CA in exceptional circumstances. Provide the CA with evidence of the competence of welders and details of the welding procedures for all loadbearing welds for agreement. When welding on site ensure the welding has adequate protection from the weather. 6.2 3.2 Quality Welding shall be carried out in accordance with the requirements of BS EN 287–1, BS EN ISO 15614, BS EN 1011–2 and Appendices 6 and 10 to the CARES Steel for the Reinforcement of Concrete Scheme, or equivalent. Details for welding of reinforcement with a carbon equivalent greater than 0.42 must be agreed with the CA. 6.2.4 Projecting reinforcement All reinforcement ends left projecting from cast concrete shall be free of release agents and shall be protected against damage and corrosion. Light surface rusting will be accepted, unless detrimental to the finished structure or causing rust staining to adjacent exposed concrete surfaces or formwork. 6.2.5 Site bending 6.2.5.1 Conditions Bending of reinforcement, including straightening, at temperatures less than -5 °C is not permitted.■ The curvature should be as constant as practicable.■ Bending should be in one operation at a constant rate.■ Reinforcement should not be warmed above 100 °C .■ The bend radius shall be not less than that given in BS 8666 and Cl. 6.3(2) of BS EN 13670: 2009■ unless the documented re-bend properties show this can be adjusted. 6.2.5.2 Agreement A method statement must be prepared for agreement with the CA. 6.2.5.3 Inspection Inspect each bar bent for any sign of fracture. Any fractured bars must be considered as non- conforming.
  • 22. NSCS Standard Specification NSCS Standard14 Section 7 Prestressed concrete construction Note: This section is for in-situ concrete post-tensioned construction. 7.1 Design and quality control 7.1.1 General To be in accordance with CARES, or equivalent, procedures unless agreed in advance with the CA. 7.1.1.1 Contractors Post-tensioning contractors shall have the necessary experience, knowledge, resources and equipment and CARES certification for the installation of post-tensioning systems in concrete structures as required by CARES Post-tensioning systems, Part 2 – The supply and/or installation of post-tensioning systems, or equivalent accredited product certification. 7.1.1.2 Operatives All post-tensioning operations shall be carried out by operatives with appropriate knowledge, training and proven experience in carrying out similar operations. Supervisors and operators shall be trained and certified to meet the requirements given in the CARES Registration scheme for post- tensioning operatives, 2007, or equivalent. Trainee post-tensioning personnel shall be adequately supervised when performing post-tensioning activities. 7.1.1.3 Quality plan Details required: Proposed materials, equipment, method statements, quality procedures, records, acceptance procedures, inspection and test arrangements. 7.1.1.4 Stressing calculations The theoretical extensions shall be calculated by the post-tensioning Contractor. However, the CA may undertake the calculations but should request the values of the necessary parameters from the post-tensioning Contractor. All relevant system data shall be stated e.g. p, k, strand E value and area, wedge draw-in on lock off and any assumed movement at dead end, etc. Extension calculations shall be submitted to the CA for acceptance at least ten working days before stressing. The CA shall confirm agreement, or comment otherwise at least five working days before stressing. 7.1.1.5 Grout testing Grout shall be tested as required by BS EN 446 and BS EN 447. 7.2 Materials 7.2.1 General To be in accordance with the relevant parts of this Specification. 7.2.1.1 Grout The properties of the grout, made with materials and plant proposed for use on site, shall be assessed for suitability for the intended purpose sufficiently in advance of grouting operations to enable adjustments to be made to the materials plant. Personnel proposed for grouting shall be suitably experienced in such work; provide details to the CA sufficiently in advance of such work to enable experience to be reviewed. Grout shall consist of pre-bagged material requiring only the addition of a measured amount of water and shall comply with the requirements of BS EN 447.
  • 23. 7: Prestressed concrete construction NSCS Standard 15 7.2.1.2 Strand Strand shall comply with BS 5896. The grade and diameter shall be specified and shall be relaxation class 2 and shall be obtained from firm(s) holding a valid CARES certificate of approval, or equivalent. 7.2.1.3 Stressing bar Bar shall comply with BS 4486. The grade and diameter shall be specified and shall be obtained from firm(s) holding a valid CARES certificate of approval, or equivalent. 7.2.1.4 Coating material (unbonded tendons) The coating to unbonded strand shall be 1 mm polypropylene unless otherwise stated in NSCS Project Specification. 7.2.1.5 Anchorages Anchorages for post-tensioning systems shall comply with the minimum performance requirements of BS EN 13391. Documentary evidence of compliance shall be provided if requested. 7.2.1.6 Ducts and vents Duct, vent and connection material shall be sufficiently robust to resist damage during construction. It should be smooth galvanised steel with a minimum wall thickness of 0.35 mm or corrugated galvanised steel with a minimum wall thickness of 0.30 mm. Where plastic ducts are used they should comply with fib Bulletin 7: Corrugated plastic ducts for internal bonded post-tensioning. Ducting shall prevent the entrance of paste from the concrete, and shall not cause harmful electrolytic action or any deterioration of the tendon or tendon components. The internal cross- sectional area of the duct shall be at least twice the net area of the tendon’s prestressing steel. Ducting shall be capable of transmitting forces from grout to the surrounding concrete. 7.2.1.7 Other materials All materials are to be in accordance with ETAG 013 Annex C. 7.3 Execution 7.3.1 Tendons 7.3.1.1 Location Unbonded tendons may be deviated to avoid obstructions such as openings and columns with the agreement of the CA. The change of direction of the tendon should occur away from the opening and trimmer bars should be provided to avoid any possible cracking at the corners in accordance with TR43 Post tensioned concrete floors – design handbook, 2004, Cl. 6.7. 7.3.1.2 Fixing and support Tendons shall be fixed and supported at centres not exceeding 1 m and shall be securely fixed to prevent movement and flotation during the construction process. 7.3.1.3 Cutting Tendons shall be cut to length using mechanical means. 7.3.1.4 Marking The actual position of tendons shall be marked on the slab soffit to indicate the location in both plan and elevation within the slab. The system of marking shall be agreed with the CA.
  • 24. NSCS Standard Specification NSCS Standard16 7.3.2 Vents Vents shall be fixed at injection and exit points and, where tendon drape exceeds 500 mm, intermediate vents shall be fixed at tendon high points. Vents shall extend approximately 500 mm above the slab surface. Intermediate vents should be used on tendons over 20 m in length. 7.3.3 Cutting or drilling into prestressed slabs Where the tendon position is not accurately and authoritatively documented, reinforcement detection equipment must be used to locate tendon positions prior to any cutting or drilling work on the slab. 7.3.4 Stressing 7.3.4.1 Jacking force The jacking force should not normally exceed 75% of the tendon’s characteristic strength but may be increased to 80% provided that additional consideration is given to safety and the load extension characteristics of the tendon. At transfer, initial prestress shall not normally exceed 70% of the tendon’s characteristic strength, and in no case shall exceed 75%. 7.3.4.2 Measurement For routine stressing, load/extensions shall be measured prior to commencement of stressing, and after stressing and locking off to an accuracy of 2% or 2 mm whichever is more accurate. Measurements shall take into consideration the possible strand movement at the dead end anchor. Any restrictions on stressing sequence and increments as specified in NSCS Project Specification shall be observed. 7.3.4.3 Commencement Stressing shall not commence without prior agreement on theoretical extensions nor before the concrete has achieved the transfer strength specified in NSCS Project Specification. The concrete transfer strength shall be based on cubes taken from the last concrete load and cured in similar conditions to the concrete to which they relate. 7.3.5 Stressing equipment Stressing jacks and their load measuring system should have an appropriate and current calibration certificate, which is traceable to national standards, and no more than 6 months old at the time of stressing. The calibration certificate should be provided by a NAMAS accredited laboratory and should include a calibration curve establishing a correlation between the values given by the measuring system and the loads applied by the jacks. The stressing equipment shall be capable of establishing a tendon load to an accuracy of ±2%. 7.3.6 Anchorage protection The method of anchorage sealing shall be agreed with the CA if not shown on the drawings. For unbonded tendons anchorage components shall be coated with grease of similar specification to that used in the tendon and a watertight cap shall be applied over the coated area. The minimum concrete end cover to the cap shall be 25 mm. 7.3.7 Grout trials Where required, full-scale grouting trials shall be carried out using the same personnel, equipment,
  • 25. 7: Prestressed concrete construction NSCS Standard 17 materials and procedures as proposed for the Works. The trial shall demonstrate that the proposed grouting method, materials and equipment fills the ducts to the satisfaction of the CA. Trials shall be undertaken as early as possible to allow proper inspection and any necessary modifications or adjustments. The details of the trials to be carried out shall be agreed with the CA. The trials shall reflect the actual duct geometry and shall include typical tendon arrangements. The tendons shall be nominally stressed to ensure that they assume the proper position with respect to the ducts. Trial beams shall normally be cut at five sections for examination but more sections may be specified for complex tendon profiles. Grouting of the ducts shall normally be shown to leave no void which has a radial dimension greater than 5% of the maximum duct sectional dimension or which poses a risk to the integrity of the tendon. Particular attention shall be given to avoiding bleed collection or void formation at high points in the ducts or anchorages. There shall be a procedure such as backup equipment or flushing out of ducts for corrective action in the event of breakdown or blockage. Where it is agreed that a grout trial is not necessary, prior to starting work on site, inform CARES, or equivalent, of the commencement of operations and request an audit of the post-tensioning works. Provide the CA with the outcome of the audit. Should the audit highlight any areas of concern, demonstrate to the satisfaction of the CA that any works carried out before the audit are not defective. 7.3.8 Grouting equipment Grouting equipment shall comply with the requirements of BS EN 446. 7.3.9 Grouting Grouting shall be in accordance with BS EN 446. 7.4 Records 7.4.1 General One copy of the following records shall be sent to the CA not more than five working days after each operation. 7.4.1.1 Anchorages Data sheets and method statements for anchorage sealing. 7.4.1.2 Tendon installation Strand source and cast number■ Anchorage batch number■ Wedge batch number■ Duct batch number■ Location of the products within the structure■ 7.4.1.3 Stressing Date of stressing■ Strength and age of concrete samples, minimum age of concrete at transfer■ Equipment calibration date, operator name■
  • 26. NSCS Standard Specification NSCS Standard18 Serial numbers of gauges and jacks■ Tendon identification■ Theoretical extension, actual extensions and corresponding loads (where required), initial and final■ jacking loads 7.4.1.4 Grouting The materials used, including batch numbers■ Grout properties including temperatures■ Ambient temperature and weather conditions■ The date and time■ Details of any interruptions and any problems encountered during the grouting process, e.g.■ blockages, loss of grout or loss of grout pressure Name of the supervisor responsible for the operation■ Records for each individual duct, including inspection of end caps and vent tubes■ Section 8 Concrete and concreting 8.1 Concrete 8.1.1 General 8.1.1.1 Standards Concrete shall conform to BS 8500–2 and BS EN 206–1, and shall be as specified in NSCS Project Specification. 8.1.1.2 Materials Portland cement, fly ash, ggbs and silica fume products shall be produced by certified suppliers operating BS EN ISO 14001 and BS OHSAS 18001 certified systems. The chloride content of the proposed concrete including chlorides contained in the admixtures shall be limited in accordance with BS EN 206–1: 2000, Cl. 5.2.7 and BS 8500–2: 2006, Cl. 5.3. Provide evidence of conformity. Calcium chloride shall not be included in any concrete. Provide evidence of conformity to the provisions to minimise the risk of damage by alkali-silica reaction given in BS 8500–2: 2006, Cl. 5.2. Recycled aggregate (RA) and recycled concrete aggregate (RCA) shall conform to BS 8500–2: 2006, Cl. 4.3. Precautions shall be taken to restrict the amount of sulfate in the proposed concrete, based on past experience or when using RCA in accordance with BS 8500–2: 2006, Cl. 4.3. No additions or changes to the fresh concrete shall be made after batching, without prior agreement of the CA. 8.1.1.3 Records Submit, as appropriate, details of the proposed concretes in accordance with BS EN 206–1: 2000, Cl. 7.2 and BS 8500–1: 2006, Cl. 5.2 to the CA for approval.
  • 27. 8: Concrete and concreting NSCS Standard 19 Daily maximum and minimum atmospheric shade temperatures shall be recorded using a calibrated thermometer(s) located close to the structure. 8.1.1.4 Site addition of water to ready-mixed concrete Water should not be added on site but IF it is added to the concrete truck mixer drum, before discharge on site, the concrete shall be deemed non-conforming – until identity testing for strength shows that the concrete is acceptable – unless the addition is made by the producer using a procedure agreed in advance with the CA. 8.1.2 Testing 8.1.2.1 Testing of fresh concrete Where required to be in accordance with BS EN 12350. 8.1.2.2 Conformity testing The concrete producer shall carry out testing of the concrete in accordance with BS EN 206 and BS 8500. Where the producer identifies a non-conformity that was not obvious at the time of delivery, this shall be reported to the CA and the Employer within 24 hours of the Constructor receiving notification. 8.1.2.3 Identity testing Inform the producer if identity testing is required by NSCS Project Specification. The criteria for acceptance will be those given in BS EN 206–1: 2000, Appendix B and BS 8500–1: 2006, Annex B5. 8.1.2.4 Compression testing Concrete test cubes prepared by the constructor, or his authorised agent, shall be manufactured, initially cured and subsequently transported to an independent laboratory, in accordance with BS EN 12390–2, for subsequent density and compressive strength testing in accordance with BS EN 12390–7 and BS EN 12390–3 respectively. The independent laboratory shall be accredited by UKAS as conforming to BS EN ISO/IEC and hold a current schedule of accreditation for the required tests. 8.1.2.5 Delivery tickets Delivery ticket information shall be in accordance with BS EN 206–1: 2000, Cl. 7.3 and BS 8500–2: 2006, Cl. 11 as relevant and shall be completed and available before discharging concrete into the structure. Where the Constructor authorises the addition of extra water this shall be recorded on the delivery ticket; see NSCS Standard Specification Cl. 8.1.1.4. All delivery tickets shall be retained by the Constructor until the structure is handed over to the Employer. Where a ticket is marked ‘non-conforming’ a copy shall be passed to both the Constructor and the CA within 24 hours of placing the concrete. 8.1.3 Plant – ready-mixed concrete 8.1.3.1 Third-party accreditation Ready-mixed concrete shall be supplied by a producer from a plant holding current accredited third-party certification meeting requirements of BS EN 206–1: 2000, Annex C. Provide the CA with confirmation of the producer’s certification in accordance with BS EN 206–1: 2000 Annex C.3. 8.1.3.2 Information required Details of a ready-mix concrete plant proposed for use shall be forwarded to the CA. Contingency plans shall be in place prior to commencement of work should supplies be interrupted during a pour due to a plant breakdown. Where feasible, details of a suitable backup plant/supplier should be submitted to the CA for agreement.
  • 28. NSCS Standard Specification NSCS Standard20 8.1.4 Plant – other concrete For supplies of concrete from sources other than plants holding current third-party certification, submit information to the CA that the production and conformity control systems used are in accordance with BS EN 206-1: 2000, Cl. 8, 9 and 10.1 and also BS 8500-2: 2006, Cl. 12 to 14. 8.1.5 Supply and transport All concrete shall be supplied and transported to the point of discharge from the mixer/agitator truck in accordance with the requirements of BS EN 206–1: 2000, Cl. 7 and BS 8500–2: 2006, Cl.14. 8.2 Concreting 8.2.1 Placing and compaction 8.2.1.1 Placing Concrete shall be placed and fully compacted so as to avoid cold joints, honeycombing and to minimise segregation, excessive blemishes or other defect in the hardened concrete. 8.2.1.2 Compaction Compaction shall be carried out without causing damage or displacement of the formwork, reinforcement, tendons, ducts, anchorages, inserts etc. 8.2.1.3 Kickers Where kickers are used, they shall be made with concrete of the same strength as that used in the wall or column, of sound construction and a minimum of 100 mm high generally and 150 mm high cast monolithically for water-resisting construction. Where kickerless construction is used provide details of the proposed method of securing and sealing the column and wall shutters at floor joints to the CA for agreement. 8.2.1.4 Premature cessation Suitable arrangements for premature cessation of a pour shall be agreed and in place before work starts. Should premature cessation of a pour arise, agree with the CA the extent and timing of any necessary remedial work before resumption of placing. 8.2.2 Concreting in extreme conditions 8.2.2.1 Cold weather For concreting in cold weather, air temperature below 5 °C, agree in advance with the CA any changes to the cement, admixtures or concrete temperature to prevent freezing of the concrete, to limit extended stiffening times and to maintain the required concrete strength development. 8.2.2.2 Hot weather For concreting in hot weather, air temperature above 30 °C, agree in advance with the CA any changes to the cement, admixtures or concrete temperature to minimize high temperature rises and reduction in the useful working life of the fresh concrete. 8.3 Curing 8.3.1 General The Curing Class is 2 in accordance with BS EN 13670, unless otherwise specified in NSCS Project Specification. The surface of the concrete shall be cured to avoid premature drying out. Methods of
  • 29. 8: Concrete and concreting NSCS Standard 21 curing shall be agreed with the CA. Curing membranes shall be compatible with any finishes to be applied subsequently. 8.3.2 Early age thermal cracking When concrete is to be placed in conditions or in an element where early age thermal cracking is likely, measures shall be adopted that minimise the risk of early age thermal cracking to a level acceptable to the CA. Ensure that the temperature of the concrete does not exceed 65 °C and that the temperature differential does not exceed the appropriate values given in CIRIA Report C660 (Bamforth, 2007), Table 7.1. Where a risk of thermal cracking is identified, the location of monitoring apparatus and interpretation of the values recorded shall be agreed with the CA prior to installation. 8.4 Inspection – post-concreting 8.4.1 General At the end of the specified period of curing, the relevant work shall be inspected by the Constructor. 8.4.2 Water-resisting construction For water-resisting construction, inspection shall be carried out jointly with the Constructor and CA before backfilling or covering up to identify defects which may lead to water penetration. Further inspection shall be jointly carried out to identify any water penetration after backfilling. 8.5 Surface cracking 8.5.1 General Take all reasonable actions to minimise surface cracking, from all causes. Where cracking occurs that it is expected will result in corrosion of the reinforcement, unacceptable water leakage, impaired durability or reduced structural adequacy, it will be rectified as agreed with the CA. Limits on cracking, unless specified in NSCS Project Specification, are: In general reinforced concrete superstructure isolated crack widths up to 0.3 mm■ In ground bearing slabs isolated crack widths up to 2.0 mm between panel joints■ In concrete slabs cast on metal deck formwork as part of a composite structure isolated crack■ widths up to 1.0 mm. 8.6 Surface finishes 8.6.1 Formed finishes An Ordinary finish is to be provided unless otherwise specified in NSCS Project Specification. 8.6.1.1 Basic finish There are no requirements for finish other than to enable adequate compaction, to provide adequate cover to reinforcement and to achieve specified tolerances. 8.6.1.2 Ordinary finish There are no special formwork requirements for this finish. Concrete should be thoroughly compacted and the formed surface should be free from major inherent blemishes and honeycombing. There is no requirement for consistency of colour for the struck surface. Surface defects may be made good subject to agreeing a method with the CA. Steps at joints between forms to be a maximum of 5 mm.
  • 30. NSCS Standard Specification NSCS Standard22 Note: This type of finish can be seen at the CONSTRUCT regional reference panels. See NSCS Guidance Cl. 8.6.1. 8.6.1.3 Plain finish A Plain concrete finish requires the careful selection of the concrete, release agent, and the use of good quality formwork. The concrete must be thoroughly compacted and all surfaces should be true with clean arrises. Only very minor inherent surface blemishes should occur, with no discolouration from the release agent or grout runs from adjacent pours. The struck surface should be of a consistent colour from the materials used. The arrangement of formwork panels and tie-bolt holes should be in a regular pattern. Steps at joints between forms to be a maximum of 3 mm. It is expected that this finish will not require making good. Details of any sample panels required are given in NSCS Project Specification. Note: This type of finish can be seen at the CONSTRUCT regional reference panels. See NSCS Guidance Cl. 8.6.1. 8.6.1.4 Special finish A Special finish requires the careful selection of the concrete, release agent, the use of good quality formwork and thorough compaction. Detailed requirements of the surface finish required, and any permitted further working or improvements to the as-struck finish are given in NSCS Project Specification. A sample panel will be required as described in NSCS Project Specification. 8.6.2 Unformed finishes A Basic finish is to be provided unless otherwise specified in NSCS Project Specification. 8.6.2.1 Basic The concrete shall be leveled by skip float, or similar process to produce a closed uniform surface. No further work shall be carried out. 8.6.2.2 Ordinary The concrete shall be finished by floating or panning or a similar process, to produce a level, uniform surface. No further work shall be carried out. 8.6.2.3 Plain The concrete shall be finished by trowelling, or a similar process, to produce a dense, smooth, level, uniform surface. No further work shall be carried out. 8.6.2.4 Special To be produced by further working of a finish or other improvements as specified in NSCS Project Specification. Section 9 Precast concrete 9.1 General This section deals with additional considerations particular to structures partly or wholly of precast construction. 9.1.1 Details The manufacturer shall operate an agreed quality management system to BS EN ISO 9000 unless agreed with the CA. Records of the unit mark, unit composition, date of casting, and curing regime
  • 31. 9: Precast concrete NSCS Standard 23 for each precast element shall be made by the manufacturer and kept available for inspection at the precast works. 9.1.2 Connections Connection details are to be compatible with the design assumptions and should allow for the expected tolerances. Details are to be submitted to the CA for agreement. 9.1.3 Erection specification and work programme An erection specification and work programme shall be prepared and agreed with the CA. 9.1.4 Identification All marks shall be made so that they are hidden when unit is placed in position, or may be removed without marking the concrete surface. 9.2 Precast concrete products Delivery notes are required for all products delivered to the site and must show relevant details of product conformity, as required by BS EN 13369 and the relevant product specification. 9.3 Precast concrete elements All site-manufactured concrete elements must conform to the requirements of Sections 5, 6, 7 & 8 of NSCS Standard Specification. 9.3.1 Striking The minimum period before removing the formwork is at the discretion of the Constructor on the basis of the assessed compressive strength of the precast element. 9.3.2 Lifting No precast element shall be lifted from the base on which it was cast before the concrete has attained its design demoulding strength and is strong enough to prevent the precast element from being damaged, overstressed or distorted giving regard to the demoulding equipment to be used. 9.4 Handling and storage 9.4.1 General Precast components shall be clearly marked before delivery in accordance with the erection specification to indicate their weight, location and orientation in the works in order to facilitate correct erection. Where delivery cannot be timed for direct final positioning, arrange suitable storage to ensure no deterioration or damage. Storage shall be on firm supports ensuring units are clear of the ground. Provide the CA with the storage proposals. 9.4.2 Protection Precast component faces to be exposed in the finished construction are to be protected from mechanical damage, dirt, staining, rust marks and other disfiguration. 9.4.3 Reinforcement and fixings The manufacturer shall determine the need for any additional reinforcement or fittings necessary for handling the precast components or other provisions required for temporary structural purposes
  • 32. NSCS Standard Specification NSCS Standard24 until the precast components are incorporated into the structure, including details for the making good of any provision made for lifting etc. Any inserts or fixings required to be cast within the concrete and permanently exposed either externally or within the cavity of the building envelope shall be of stainless steel unless otherwise accepted by the CA. In other cases any protective treatment shall be as agreed with the CA. 9.5 Placing and adjustment 9.5.1 Temporary stability Ensure that any precast concrete component to be incorporated into the structure shall be kept stable in its erected position until such time as the component can safely carry the construction loads without distress. The overall stability of the structure shall be maintained at all times during the erection process. 9.5.2 Bearings for precast products Are to be level and not less than the minimum recommended by the manufacturer. 9.5.3 Cutting and drilling precast products Submit proposals, agreed with the manufacturer, for acceptance by the CA. 9.5.4 Alignment of units The units shall be positioned in the Frame to the tolerances given in Section 10, Geometric tolerances. 9.6 Jointing 9.6.1 General All jointing to be as shown on the erection specification or agreed with the CA. 9.6.2 Materials Grout material to comply with BS EN 197–1 and BS EN 13139. Section 10 Geometric tolerances 10.1 General The tolerances given in this section are NOT cumulative. Carry out regular checks on the structure. If an element size or position is out of tolerance propose remedial measures for agreement with the CA. 10.1.1 Precedence The following are the permitted tolerances for the structure as defined on the drawings. These tolerances take precedence over those given in BS EN 13670. All appropriate BS EN 13670 tolerances have been repeated for completeness of NSCS Standard Specification. The tolerances for position refer to the tolerance from the reference lines and datum given in NSCS Project Specification. Any deviation in secondary lines are included in the tolerances given.
  • 33. 10: Geometric tolerances NSCS Standard 25 The hierarchy of tolerance adopted in the NSCS is such that the tolerance of each level must be contained within the tolerance level of the level above where 1 is the highest level: First – The overall tolerance of the structure, Cl. 10.2, 10.3 and 10.4■ Second – The positional tolerance of all parts of elements of the structure within the overall■ tolerance, Cl. 10.5 and 10.6 Third – The dimensional tolerance of the individual elements within their positional tolerance,■ Cl. 10.7, 10.11 and 10.12 Fourth – The position tolerance of reinforcement and fixings within the individual elements■ dimensional tolerance, Cl. 10.8, 10.9 and 10.10 10.1.2 Tolerance class Tolerance Class 1 is considered to be the normal tolerance as set out in BS EN 13670. Lesser deviations to meet design, fit requirements or any other reason shall be considered Class 2 and the required deviations are given in NSCS Project Specification. Class 2 tolerances specified in NSCS Project Specification may apply to the whole structure or any part. 10.1.3 Execution class Where Class 2 tolerances are given in NSCS Project Specification the execution will be to Execution Class 3. 10.1.4 Measurement The tolerances given in Cl. 10.2.2, 10.6.5 & 10.6.6 below apply before the striking of the formwork. The tolerances given are before deformation caused by loading and time-dependent effects. 10.1.5 Reference grids The location of the reference grids or primary lines and levels for the overall positioning of the Works shall be agreed by the CA and the Constructor before the structure is set out. 10.1.6 Box principle The ’box principle’ can be applied to the tolerances in NSCS Standard Specification. Where it is applied to the whole building the tolerances is as given by Cl. 10.2.1; where it is applied to an individual element the tolerance is ± 20 mm. 10.2 Overall structure 10.2.1 Inclination Location of any column, wall or floor edge, at any storey level, from any vertical plane through its intended design centre at base level in a multi-storey structure. H D h3 h2 h1 Permitted deviation D = the smaller of 50 mm or H/(200n1/2) mm where h = free storey height in mm H = free height at location = Shi in mm n = number of storeys where n > 1
  • 34. NSCS Standard Specification NSCS Standard26 10.2.2 Level Level of floors measured relative to the intended design level at the reference level. H + D Permitted deviation D for H ≤ 10 m = 15 mm 10 m < H < 100 m = 0.5(H + 20) mm H ≥ 100 m = 0.2(H + 200) mm where H = sum of the intended storey heights in m 10.3 Base support (foundations) Base supports shall include direct foundations and pile caps, etc. but not deep foundations such as piles, slurry walls, diaphragms, special anchorages, etc. 10.3.1 Plan section lx + D ly + D x y Permitted deviation D = 25 mm where lx = intended position in the x direction ly = intended position in the y direction 10.3.2 Vertical section Position in the vertical direction of a base support relative to the intended design position. h + D Permitted deviation D = 20 mm where supporting concrete superstructure Permitted deviation D = –15 mm + 5 mm where supporting steel superstructure where h = intended distance of foundation below datum level 10.4 Foundation bolts and similar inserts Note: Deviations are coordinated with BS EN 1090–2: 2008 Cl. D.2.20.
  • 35. 10: Geometric tolerances NSCS Standard 27 10.4.1 Preset bolt prepared for adjustment Dy, Dz Dy Dz Dp ■ Distance of centre of a bolt group from intended design position Permitted deviation = 6 mm Location of bolt at tip, from centre of bolt group■ Permitted deviation Dy, Dz = 10 mm Protrusion■ Permitted deviation Dp: –5 mm ≤ Dp ≤ 25 mm 10.4.2 Preset foundation bolt not prepared for adjustment Dy, Dz Dy, Dz Dp Dy Dx Dz Distance of centre of a bolt group from■ intended design position Permitted deviation = 3 mm Location of bolt at tip, from centre of bolt group■ Permitted deviation Dy, Dz = 3 mm Vertical protrusion■ Permitted deviation Dp: –5 mm ≤ Dp ≤ 45 mm Horizontal protrusion■ Permitted deviation Dx: –5 mm ≤ Dx ≤ 45 mm 10.5 Elements – columns and walls The deviation or sum of any deviations of any individual element must not exceed the overall building structure tolerance given in 10.2. 10.5.1 Position on plan Position of the element centre line relative to: At base level the intended design position.■ At any upper level the actual location of the element at the level below.■ lx + D ly + D x y Permitted deviation D = 10 mm where l = distance to centreline from grid line
  • 36. NSCS Standard Specification NSCS Standard28 10.5.2 Verticality by storey of the structure Inclination of a column or wall at any level in a single- or multi-storey building. h D Permitted deviation D for h ≤ 10 m = the larger of 15 mm or h/400 h > 10 m = the larger of 25 mm or h/600 where h = height of element in mm 10.5.3 Offset between floors Deviation between centrelines at floor level. t1 t2 D Permitted deviation D = the larger of 10 mm or t/30 mm, but not more than 20 mm where t = thickness in mm = (t1 + t2) / 2 10.5.4 Curvature between adjacent floors Curvature of an element between adjacent storey levels. h D Permitted deviation D for h ≤ 10 m = the larger of 15 mm or h/400 h > 10 m = the larger of 25 mm or h/600 where h = height of element in mm 10.5.5 Level per storey of structure Level of adjacent floors at supports. h + D Permitted deviation D = 10 mm where h = storey height in mm
  • 37. 10: Geometric tolerances NSCS Standard 29 10.5.6 Distance between adjacent columns and walls Distance between adjacent columns and walls, measured at corresponding points. l + D Permitted deviation D = the larger of 20 mm or l/600 mm, but not more than 40 mm where l = distance between centrelines in mm 10.6 Elements – beams and slabs 10.6.1 Location of beam to column connection Location of a beam to column connection measured relative to the column. b Beam Column Centreline of beam Centreline of column D Permitted deviation D = the larger of 20 mm or b/30 mm where b = dimension of column in the same direction as D in mm 10.6.2 Position of bearing axis of support Position of bearing axis of support when structural bearings are used. l + D Actual bearing axis of support Permitted deviation D = the larger of 15 mm or l/20 mm where l = intended distance from edge in mm 10.6.3 Straightness of beams Horizontal straightness of beams. lD Permitted deviation D = the larger of 15 mm or l/600 mm where l = distance between supports
  • 38. NSCS Standard Specification NSCS Standard30 10.6.4 Distance between adjacent beams Distance between adjacent beams, measured at corresponding points. l + D Permitted deviation D = the larger of 20 mm or l/600 mm, but not more than 40 mm where l = distance between support centrelines in mm 10.6.5 Inclination of beam or slab Difference in level across a beam or slab at corresponding points in any direction. l D Permitted deviation D = (10 + l/500) mm where l = span of element in mm 10.6.6 Level of adjacent beams Level of adjacent beams, measured at corresponding points. l D Permitted deviation D = (10 + l/500) mm where l = distance between support centrelines in mm 10.6.7 Position of slab edge Position of slab edge relative to actual slab edge position on the floor below. D Permitted deviation D = 10 mm
  • 39. 10: Geometric tolerances NSCS Standard 31 10.7 Section of elements 10.7.1 Cross-section dimension of elements Applicable to beams, slabs, columns and other elements covering length, breadth and depth. l2 ± D l1 ± D Permitted deviation D = for l ≤ 150 mm = 10 mm l = 400 mm = 15 mm l ≥ 2500 mm = 30 mm with linear interpolation for intermediate values where l1, l2 = intended dimensions 10.7.2 Squareness of element Applicable to beams, slabs, columns and other elements. a D Permitted deviation D = the larger of 10 mm or a/25 mm, but not more than 20 mm where a = length in mm 10.8 Position of reinforcement within elements 10.8.1 Location of reinforcement Gives the tolerance of cover to reinforcement within an element. cnom cmin D(plus) D(minus) Permitted deviation D(plus) for h ≤ 150 mm = +10 mm h = 400 mm = +15 mm h ≥ 2500 mm = +20 mm Permitted deviation D(minus) = 10 mm where cmin = required minimum cover cnom = nominal cover given on drawings D = permitted deviation from cnom h = height of cross section For foundations and members in foundations, permitted plus-deviations maybe increased by 15 mm. The given minus- deviations apply. 10.8.2 Length of reinforcement lap joints l + D Permitted minus-deviation D = 0.06l mm where l = intended lap length in mm
  • 40. NSCS Standard Specification NSCS Standard32 10.8.3 Location of reinforcement and ducts in prestressed elements h y + D ■ Anchorages Permitted location deviation D = 25 mm horizontally 5 mm vertically Tendons■ Permitted deviation D Horizontally in beams = 0.03h (width) ≥ 5 mm ≤ 30 mm in slabs = 150 mm Vertically D(plus) if h < 200 mm = +h/40 if h > 200 mm = +15 mm D(minus) all h = –10 mm where h for vertical section = depth in mm h for plan section = width in mm y = intended location in mm 10.9 Surface straightness 10.9.1 Flatness Flatness of surface of any element. l D ■ Basic unformed surface (Cl. 8.6.2.1) Permitted global deviation D = 12 mm Permitted local deviation D = 5 mm Ordinary unformed surface (Cl. 8.6.2.2)■ Permitted global deviation D = 9 mm Permitted local deviation D = 3 mm Ordinary surfaces (Cl. 8.6.1.2)■ Permitted global deviation D = 9 mm Permitted local deviation D = 5 mm Plain surfaces (Cl. 8.6.1.3)■ Permitted global deviation D = 9 mm Permitted local deviation D = 3 mm 10.9.2 Edge straightness Straightness of edge of floor slab or element. l D Permitted deviation D for l < 1 m = 8 mm l > 1 m = 8 mm/m, but no greater than 20 mm where l = length of edge
  • 41. 10: Geometric tolerances NSCS Standard 33 10.10 Holes and fixings 10.10.1 Holes Size and location of hole relative to design position. l1 l1 l2 l2 l2 l2 x y ■ Position Permitted deviation D1 = 10 mm where l1 = intended distance to centre line Size■ Permitted deviation D2 = l2 ≤ 150 mm = 6 mm l2 = 400 mm = 15 mm l2 ≥ 2500 mm = 30 mm with linear interpolation for intermediate values where l2 = intended dimension 10.10.2 Cast-in fixings Location of fixing or groups relative to the intended design position. D1 D1 Target Actual l2 l2 D2 ■ Deviation in plane Permitted deviation D1 = 10 mm Deviation in depth■ Permitted deviation D2 = 10 mm 10.10.3 Cast-in bolts and similar fixings Location of fixing or groups relative to the intended design position. l1 ± D1 l2 ± D2 = = == l2±D2 Location of fixing or groups relative to the intended■ design position Permitted deviation D1 = 6 mm where l1 = distance between bolt groups Internal distance between fixings in a group relative■ to the intended design position Permitted deviation D2 = 3 mm where l2 = distance between bolts Protrusion of fixing■ Permitted deviation = D(plus)+ 25 mm D(minus) – 5 mm
  • 42. NSCS Standard Specification NSCS Standard34 l3 D3 Inclination of fixing■ Permitted deviation D3 = greater of 5 mm or l3/200 mm where l3 = height of bolt 10.11 Staircases The permitted deviation in the height of any riser is 5 mm of the intended design value. The permitted deviation in the length of any going is 5 mm of the intended design value. 10.12 Precast concrete elements 10.12.1 Standard precast products Standard precast products shall comply with the tolerances given in the relevant product standards. 10.12.2 Project designed precast elements Concrete elements produced for the project shall comply with the tolerances for: sections of elements; position of reinforcement within elements; surface straightness; and holes and fixings given above.
  • 43. National Structural Concrete Specification for Building Construction Fourth edition complying with BS EN 13670: 2009 NSCS Project Specification
  • 44. NSCS Project Specification36 NSCS Foreword The Specification that follows shows what is required in a Project Specification using the NSCS Standard Specification. This specification as shown in this document is not intended to be completed. An interactive copy of the Project Specification has been produced for electronic completion without infringement of copyright. The interactive NSCS Project Specification is available by downloading from www.construct.org.uk or by obtaining a CD from CONSTRUCT, Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surrey GU17 9AB, UK Tel +44 [0]1276 38444 Fax +44 [0]1276 38899 Email enquiries@construct.org.uk
  • 45. NSCS Project Specification 37 Project Specification NSCS Project Specification i) The specification for the structure shall be the National Structural Concrete Specification for Building Construction (NSCS). ii) The NSCS Project Specification is provided by the Employer and identifies the appropriate information specific to the structure over and above that stated in NSCS Standard Specification. Clauses in the Standard Specification may be modified by information given in the Project Specification. Project name Project ref. Revisions Revision Date Clauses Notes Deleted Amended Added Prepared by Date
  • 46. NSCS Project Specification38 NSCS Section P1 Information to be supplied TO the Constructor P1.1 General information P1.1.1 Project contacts Project name Project ref. Address Employer Name Address Contact name Telephone Email Principal Contractor Name Address Contact name Telephone Email Engineer Name Address Contact name Telephone Email Contract administrator (CA) Name Address Contact name Telephone Email Other named parties to the Contract: Name Name P1.1.2 Description of the project works Nature of building and intended use, number of floors, column grids, stair and core, stability system, foundations, basements, location of water-resisting construction, special finishes, relevant project sustainability targets and procedures, etc.
  • 47. Project Specification NSCS Project Specification 39 P1.1.3 Construction planning requirements Note: the information here is largely reproduced from the Contract Documents to assist the Constructor in the preparation of Section P2. The Constructor should notify the CA if any discrepancy is identified between the Contract Documents and the Specification. Where details of the site conditions are provided, such as underground services, overhead cables, adjacent buildings and site obstructions, they are given to assist the Constructor in their tender stage planning. The Constructor should always confirm the accuracy of this information when on site, before starting work. General Positions of the Reference Line (as defined in BS EN 13670) datum level and setting-out lines, width and level of access, level of the prepared working area for site traffic, cranes and pumps, and areas available for storage and site accommodation are shown on drawing numbers: Details of underground services, overhead cables, adjacent buildings, site obstructions or other constraints on the Constructor: Availability of site services and any prearranged procedures for sole or shared use: Factors affecting construction sequence, including working restrictions on time or special nuisance (including noise); or other aspects that may create an unusual hazard: Special requirements for temporary propping: Restrictions on dimensions and/or weights of units to be delivered to site: Interface requirements/restrictions between the works and following trades: Special requirements for headroom: A programme showing clearly any phased requirements and the earliest and the latest release dates of work to following trades or to the Employer is shown on drawing numbers: Access will be made available to the Constructor on: Environmental factors relating to achievement of Considerate Constructors or Site Waste Management requirements:
  • 48. NSCS Project Specification40 NSCS P1.2 Design P1.2.1 General The design has been carried out in accordance with BS EN 1990, BS EN 1991 and BS EN 1992. Any design by the Constructor is to be carried out in accordance with these codes and the design data given in this specification. P1.2.2 Loading Loading (kN/m2) Location Location Location Location Location Imposed General Partitions Total imposed Dead load Self-weight Partitions Flooring Screed Services Ceiling Total dead load Cladding Wind Other P1.2.3 Other design data Design data Location Location Location Location Location Fire rating (hours) Exposure Class Design life (years) Maintenance/replacement assumptions Other P1.2.4 Special requirements for composite structures
  • 49. Project Specification NSCS Project Specification 41 P1.3 Drawings and calculations Project values should be entered in the grey panels. Item Preparation Tender issue Acceptance issue Construction issue Type1 Prepared by Format2 Number of copies Number of copies Period before construction (weeks) Number of copies Period before construction (weeks) Project Default Project Default Project Default Project Default Project Default Project General arrangement drawings RC CA 2 5 11 PCP CA 2 5 11 PCE CA 2 5 11 PSC CA 2 5 11 Design Information drawings RC CA 5 11 PCP CA 5 11 PCE CA 5 11 PSC CA 5 11 Construction sequence info All CA 2 5 11 Design calculations RC Constructor 3 8 5 5 PCP Manufacturer 3 8 5 5 PCE Constructor 3 8 5 5 PSC Constructor 3 8 5 5 Specialist drawings RC Enter CA or Constructor 3 8 5 5 PCP Constructor 3 8 5 5 Enter details as required PCE Constructor 3 8 5 5 PSC Constructor 3 8 5 5 Reinforcement detail drawings and schedules RC Enter CA or Constructor 3 7 5 5 Precast concrete elements PCP Manufacturer PCE Constructor 3 3 5 3 PSC Constructor 3 3 5 3 Builders’ work information All CA 3 3 Coordinated builders’ work drawings All Enter CA or Constructor 3 3 5 2 Temporary works and erection drawings and/or calculations and method statements All Constructor 3 3 5 2 As-built drawings All Enter CA or Constructor 3 Months after completion 3 Footnotes 1 Types of construction: RC: Reinforced concrete PCE: Precast concrete elements PCP: Precast concrete products in accordance with product standards PSC: Prestressed concrete 2 Enter P = paper; E = electronic; B = both
  • 50. NSCS Project Specification42 NSCS P1.4 Execution management P1.4.1 Execution Class The following parts of the structure are to be constructed in accordance with execution Class 3: P1.4.2 Execution documentation The following documentation is required: Project values should be entered in the grey panels. Information When required Number of working days before construction with updates as requested unless noted Format/Notes P = Paper E = Electronic B = Both Default Project Default Project Contractor’s Quality Assurance Certification At tender Paper SpeCC registration, or equivalent As requested Paper Detailed construction programme 20 Paper Falsework and formwork: design 20 Calculations & drawings Falsework and formwork: pre-concreting cleanliness As requested Paper Reinforcement: source and supplier 20 Paper Reinforcement: Certification 20 Paper Reinforcement: pre-concreting location As requested Paper Spacers As requested Paper Couplers: source and supplier 20 Paper Couplers: Certification 20 Paper Continuity strips: source and supplier 20 Paper Continuity strips: Certification 20 Paper Post-tensioning work: Certification 20 Paper Specific quality plan 20 Paper Other information As Cl. P1.14 Paper Concrete: ready-mix plant details 20 Paper Concrete: ready-mix producers’ certification 20 Paper Concrete: delivery ticket As requested Paper Concreting: method statement and pour sequence for each section of the work 5 Paper Precast concrete As Table P1.10 Paper As-built geometry: setting out and dimensions 10 working days after the construction is complete at each level Paper As-built geometry: reinforcement cover As requested Cover meter survey Environmental certification and responsible sourcing documentation where required: relating to reinforcement, aggregate, cementitious materials, formwork and concrete supply 20 Paper
  • 51. Project Specification NSCS Project Specification 43 P1.4.3 Approvals timing The timings given in NSCS Standard Specification apply to all approvals except as noted below. Project values should be entered in the grey panels. Standard Specification clause ref. Item Requirements Before or after as appropriate Working days unless stated Default Project 4.1.2.1 Material test results 10 4.2.1 Quality plan 5 4.3.3 Notice to CA for concrete pour inspection 1 4.3.3 Before prestressing work starts 1 4.3.3 Before covering up or backfilling 5 4.3.3 For water-resisting construction to allow joint inspections 5 4.3.4 Response by CA to request for modifications 5 4.3.7 Copies of test results 3 No. 4.3.8 Proposal and response time for work rectification 5 & 5 6.2.1 Notice to CA for site changes to reinforcement 1 7.1.1.4 Extension calculations for post-tensioning tendons 10 7.3.1.1 Notice to CA for site changes to post-tensioning tendons 1 7.4.1 Grouting records 5 8.1.2.1 Concrete non-conformity 24 hours 8.2.1.3 Method of fixing kickerless shutters 5 8.2.1.4 Premature cessation of a pour 2 hours 9.1.2 Precast connection details 15 9.1.3 Precast erection specification and work programme 5 9.5.3 Proposals for cutting standard precast products 5 Other P1.4.4 Inspection Items not defined in table 1 of BS EN 13670 shall be inspected as follows: Additional third-party inspection, carried out by is required of the following parts of the structure: P1.4.5 Documents The following special documentation is required: Requirements for responsible sourcing documentation:
  • 52. NSCS Project Specification44 NSCS P1.4.6 As-built geometry The overall concrete dimension shall be checked: List of requirements Frequency The cover to reinforcement shall be checked: List of requirements Frequency P1.4.7 Curing class List where curing classes other than 2 shall be used: Class Location P1.4.8 Protection The following special protection is required: P1.5 Materials P1.5.1 Reinforcement Stainless steel reinforcement shall be used in the following locations: Epoxy coated steel reinforcement shall be used in the following locations: Anchorages and couplers shall be: Fibres shall be used as follows: Type of fibres Location & dosage Requirements for responsible sourcing of reinforcement: P1.5.2 Timber Requirement for responsible sourcing of timber or timber products:
  • 53. Project Specification NSCS Project Specification 45 P1.5.3 Other materials Materials not permitted: Materials requiring special consideration: Items supplied by the Employer: Requirement for responsible sourcing of materials: Materials to be supplied under Constructor-specified supply: P1.6 Project requirements Enter variations from NSCS Standard Specification Standard Spec. clause ref. Change N: new D: deleted M: modified Description P1.7 Water-resisting construction P1.7.1 Detail The required performance for water-resisting construction is to be achieved by the use of materials and details listed below and as shown on construction drawings. Location Detail Waterstops Separation membranes Joint fillers Manufacturer Material Slab: horizontal construction joints Type Slab: horizontal movement joints Type Wall: horizontal slab/wall junction Type Wall: vertical construction joint Type Wall: vertical movement joint Type or Constructor selection and installation of materials and systems, as appropriate, to achieve a Grade environment using the grade classification in BS 8102: 2009, Table 2. The water table classification in accordance with BS 8102: 2009, Table 1 is The risk associated with groundwater is considered to be Note: Section P2.6 to be completed. P1.7.2 Crack widths These should be should be limited to mm.
  • 54. NSCS Project Specification46 NSCS P1.8 Concrete P1.8.1 Designated concrete To be In accordance with BS 8500–2 and BS EN 206–1 Project values should be entered in the grey panels. Requirements Defaults Project Project Project Project 1 Concrete designation (Ref. BS 8500–2: 2006, Table 5) 2 Maximum aggregate size (mm) Enter 10, 14, 20 or 40 20 3 Consistence class S1, S2, S3, S4 or other value S3 4 Special restrictions on cement types (enter reference if required) None 5 Special requirements for aggregates (enter reference if required) None 6 Use of RCA permitted? Maximum mass fraction of total coarse aggregate enter a higher mass fraction of total coarse aggregate, where permitted (Ref. BS 8500–1: 2006, Cl. 4.2.3c) Yes 20% 7 Requirements for accelerated or retarded set None 8 Special colour requirements None or see S1.9 None 9 Type and dosage of fibres See P1.5.1 10 Chloride class Cl 1,0 for GEN series, Cl 0,20 for SRPC, Cl 0,40 for all other concretes or enter special requirements As BS 5800–1 11 Minimum air content None 12 Method of placing concrete 13 Requirement for finishing concrete See P1.9 14 Identity testing for consistence or other properties required in accordance with BS EN 206–1: 2000 Annex B and BS 8500–1: 2006 Annex B ) (If YES then details to be added into P1.13) No Notes 1 All sections of the Specification must be completed before it is passed to the Producer. The person sending the final specification to the producer must send copies of the document to all other parties (CA, Engineer, Employer, as appropriate) who have contributed to the Specification. 2 Where ‘None’ is entered in the table this is a default value to ensure that the Specification is complete. All those involved in completing the specification need to check if ‘None’ is appropriate. 3 Guidance on specification of designated concrete can be found in BS 8500–1: 2006, Section 4.2.
  • 55. Project Specification NSCS Project Specification 47 P1.8.2 Designed concrete To be in accordance with BS 8500–2 and BS EN 206–1. Project values should be entered in the grey panels. Requirements Defaults Project Project 1 Concrete reference 2 Strength class 3 Maximum water-cement ratio 4 Minimum cement content kg/m3 5 DC-Class where appropriate 6 Permitted cement types – See BS 8500–1: 2006, Cl. 4.3.2, Note 3 7 Maximum aggregate size (mm) – Enter 10, 14, 20 or 40 20 8 Chloride class (a value must be entered unless Cl 0,40 is acceptable) Cl 0,40 9 Target density/density class (for lightweight and heavyweight concrete) N/A 10 Consistence class S1, S2, S3, S4 11 Method of placing concrete 12 Requirement for finishing concrete See P 1.9 13 Type and dosage of fibres See P1.5.1 14 Use of RA conforming to BS 8500–2: 2006, 4.3, permitted? If YES: enter requirements for the following in P1.13: Yes Maximum acid-soluble sulfate, method for determination of the chloride content classification with respect to ASR, method for determination of alkali content, any limitations on use in concrete, e.g. exposure classes, maximum mass fractions, etc. (Enter details in P1.13) RCA permitted to 20% mass fraction 15 Special requirements for aggregates None 16 Minimum air content, or other requirements to resist freeze-thaw attack None 17 Special requirements for temperature of fresh concrete None 18 Special requirements for strength development None 19 Special requirements for heat development during hydration None 20 Special requirements for retarded stiffening None 21 Special requirements for resistance to water penetration None 22 Special requirements for resistance to abrasion None 23 Requirements for tensile splitting strength None 24 Additional technical requirements See BS 8500–1: 2006, Cl. 4.3.3 sections n & m None 25 Identity Strength testing required? (If YES then details to be added into P1.13) None 26 Identity Consistence testing required? (If YES then details to be added into P1.13) None 27 Other properties Identity testing required? (If YES then details to be added into P1.13) None Notes 1 All sections of the specification must be completed before it is passed to the producer. The person sending the final specification to the producer must send copies of the document to all other parties (CA, Engineer, Employer as appropriate) who have contributed to the specification. 2 Where ‘None’ is entered in the table this is a default value to ensure that the specification is complete. All those involved in completing the specification need to check if ‘None’ is appropriate. 3 Guidance on specification of designed concrete can be found in BS 8500–1: 2006, Section 4.3.

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