Autoclaved Aerated Concrete Autoclaved Aerated Concrete Properties, Testing and Design RILEM Recommended Practice RILEM Technical Committees 78-MCA and 51-ALC Edited by: S. Aroni, G.J. de Groot, M.J. Robinson, G. Svanholm and F.H. Wittman LONDON AND NEW YORK Taylor & Francis 2 Park Square, Milton Park, Abingdon, Oxon, 0X14 4RN First edition 1993 Transferred to Digital Printing 2005 © 1993 RILEM Typeset in 10/12pt Times by Excel Typesetters Company Bury St. Edmunds, Suffolk ISBN 0 419 17960 7 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page. 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A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication data available Contents Introduction XV PART ONE RECOMMENDED PRACTICE 1 1 Introduction 3 1.1 Scope 3 1.2 Terminology 3 1.3 Classes 4 1.4 Principles of control 4 1.5 Confidence levels and probabilities 5 References 5 2 Production and structure of the material 6 2.1 Production 6 2.2 Structure of the material 8 2.3 Environmental implications 9 References 11 3 Properties of the material 12 3.1 Introduction 12 3.2 Density 12 3.3 Mechanical properties of AAC 12 3.3.1 Compressive strength 12 3.3.2 Direct tensile strength 15 3.3.3 Modulus of rupture (tensile strength in bending) and splitting tensile strength 15 3.3.4 Shear strength 16 3.3.5 Fracture mechanics parameters 16 3.3.6 Deformability 18 3.4 Moisture content and moisture transfer 22 3.4.1 Introduction 22 3.4.2 Water vapour transfer 23 3.4.3 Liquid water transfer 25 3.5 Volume changes caused by temperature, moisture and load 26 3.5.1 Thermal volume change 26 3.5.2 Drying shrinkage 27 3.6 Thermal properties 30 vi Contents 3.6.1 Thermal conductivity 30 3.6.2 Specific heat 31 3.6.3 Behaviour at high temperatures 31 3.7 Durability 32 3.7.1 General 32 3.7.2 Resistance to freezing 33 3.7.3 Resistance to sulphate attack 34 3.7.4 Resistance to attack by liquids 34 3.7.5 Resistance to attack by gases 34 3.7.6 Resistance to attack from biological sources 35 3.8 Reinforcement 35 3.8.1 General remarks 35 3.8.2 Reinforcement requirements 35 3.8.3 Anchoring of reinforcement and bond strength 36 3.8.4 Protection of structural reinforcement against corrosion 36 3.9 Interface properties 36 3.9.1 AAC/reinforcement interface 36 3.9.2 Connections of blocks and elements 37 3.9.3 Surface finishing 37 3.10 Acoustic properties 37 3.10.1 Sound insulation 37 3.10.2 Sound absorption 40 3.11 Environmental conditions 40 3.11.1 Introduction 40 3.11.2 Chemical composition 41 3.11.3 Check of hazardous materials 42 3.11.4 Assessment of radioactivity 42 3.11.5 Emittance of gases 43 3.11.6 Silicosis hazards 43 3.11.7 Handling and installing 43 3.11.8 Waste from production 43 References 44 4 Structural design 47 4.1 General introduction, safety and serviceability 47 4.1.1 Introduction 47 4.1.2 Level of safety 47 4.1.3 Limit states 47 4.1.4 Control of safety 48 4.2 Design principles 48 4.2.1 Ultimate limit states 48 4.2.2 Design load effects 49 4.2.3 Design resistance (capacity) 49 Contents vii 4.2.4 Typical global safety coefficients 50 4.2.5 Serviceability limit states 50 4.3 Control of safety by testing 52 4.3.1 Values declared by the manufacturer 52 4.3.2 Requirements for the ultimate limit state 52 4.3.3 Requirements for the serviceability limit state 53 4.3.4 Testing 53 4.3.5 Test frequency and characteristic loadbearing capacity 53 Reference 54 5 Structural analysis of elements 55 5.1 General statements 55 5.2 Stress-strain relations 55 5.2.1 General 55 5.2.2 Stress-strain relation for A AC 55 5.2.3 Stress-strain relation for steel 55 5.3 Ultimate limit states 56 5.3.1 Anchorage failure 56 5.3.2 Bending failure 58 5.3.3 Shear failure 58 5.4 Serviceability limit states 61 5.4.1 Deflection 61 5.4.2 Crack formation 64 5.5 Axially loaded units 64 5.5.1 Design criteria 65 5.5.2 Loadbearing capacity 65 5.5.3 Supports 66 References 66 6 Design of unreinforced masonry 68 6.1 Block masonry designed by calculations 68 6.1.1 Introduction 68 6.1.2 Scope 68 6.1.3 Basis of design 68 6.1.4 Stability 69 6.1.5 Loads 69 6.1.6 Design loads 69 6.1.7 Characteristic compressive, flexural and shear strength of AAC masonry 69 6.1.8 Partial safety factor for material strength 70 6.2 Design by calculation: detailed considerations 70 6.2.1 Slenderness ratio 70 6.2.2 Horizontal or vertical lateral supports 70 viii Contents 6.2.3 Lateral support 71 6.2.4 Effective height or length 71 6.2.5 Effective thickness 71 6.2.6 Cavity walls 72 6.2.7 Eccentricity at right angles to the wall 72 6.3 Walls subjected to vertical loading and shear 72 6.3.1 Design strength of masonry 72 6.3.2 Design vertical load resistance of walls 73 6.3.3 Calculation of fi 73 6.3.4 Design vertical load resistance of cavity walls 75 6.3.5 Walls subjected to shear forces 75 6.3.6 Concentrated loads: stresses under and close to a bearing 75 6.4 Walls subjected to lateral load 76 6.4.1 General 76 6.4.2 Support conditions and continuity 76 6.4.3 Limiting dimensions 77 6.4.4 Calculation of design moments in panels 78 6.4.5 Calculation of design moment of resistance of panels 79 6.4.6 Design lateral strength for cavity walls 79 6.5 Block masonry: designed by simple rules 79 6.5.1 Scope 79 6.5.2 Field of application 79 6.5.3 Definitions 81 6.5.4 Stability and robustness 81 6.5.5 Loads, strengths and dimensions 81 6.5.6 Thicknesses of walls 86 6.5.7 Rules for stiffening walls, piers and chimneys 88 6.5.8 Departure from the rules 90 6.5.9 Walls subjected mainly to wind load 90 6.5.10 Internal non-loadbearing walls 95 6.5.11 Chases and recesses 96 6.5.12 External walls of certain small, single-storey buildings and annexes 97 References 97 7 Seismic design 99 7.1 Introduction 99 7.1.1 General 99 7.1.2 Material characteristics and applications 99 7.2 Structural analysis 100 7.2.1 Building configuration 100 Contents ix 7.2.2 Application of seismic action 100 7.2.3 Analytical model 100 7.2.4 Equivalent static analysis 101 7.3 Design actions 101 7.4 Design and verification 101 7.4.1 Structural walls 101 7.4.2 Diaphragm effect of floors and roofs 102 7.5 Detailing, execution, use 103 7.5.1 Non-loadbearing applications, examples of tested detailing 103 7.5.2 Types of non-loadbearing wall installation methods 104 7.5.3 Example of details for low-rise buildings of AAC panels 108 7.5.4 Behaviour of AAC in past earthquakes 108 References 113 8 Connections and fixtures 115 8.1 General requirements 115 8.2 Connections for reinforced components 115 8.2.1 Non-loadbearing horizontal wall components 115 8.2.2 Vertical wall components 130 8.2.3 Floor and roof slabs 139 8.3 Connections for masonry 141 8.3.1 Interconnection of the masonry units 141 8.3.2 Connection of supporting walls 145 8.3.3 Connection to the floors and roof 146 8.3.4 Connections for non-loadbearing walls 149 8.3.5 Connections for infill masonry of half-timber constructions 153 8.3.6 Connections for cavity walls 154 8.4 Fixtures 155 8.4.1 General 155 8.4.2 Fastening elements for non-structural applications 157 8.4.3 Fastening elements for structural applications 162 References 167 9 Non-structural performance design 170 9.1 General 170 9.2 Thermal design 171 9.2.1 Introduction 171 9.2.2 Basic concepts 171 9.2.3 Thermal transmittance in steady-state conditions 171 9.2.4 Thermal inertia 173