Demolition and reuse of concrete and masonry: guidelines for demolition and reuse of concrete and masonry: proceedings of the Third international RILEM symposium on demolition and reuse of concrete and masonry held in Odense, Denmark, 24-27 October 1993

Demolition and Reuse of Concrete and Masonry

Related books on recycling and demolition Demolition and Reuse of Concrete and Masonry Edited by Y.Kasai With the increase in demolition on congested urban sites, the construction industry has been obliged to develop more efficient demolition techniques which are quieter and less intrusive: This book deals with the theoretical and pracitcal aspects of demolition of concrete and masonry buildings and the recycling of demolished materials. It forms the Proceedings of the Second International RILEM Symposium held in 1988 in Tokyo. Hardback (0 412 32110 6), 2 volumes, 814 pages Recycling of Demolished Concrete and Masonry Edited by T.C.Hansen This RILEM Report contains state of the art reviews on three topics: recycling of demolished concrete, recycling of masonry rubble, and localized cutting by blasting of conrete. It has been compiled by RILEM Technical Committee 37-DRC, and draws on research and practical experience worldwide. Hardback (0 419 15820 0), 316 pages For information on these and other titles, contact The Promotion Department, E & FN Spon, 2–6 Boundary Row, London SE1 8HN, Tel: 071–865 0066.

Demolition and Reuse of Concrete and Masonry Guidelines for Demolition and Reuse of Concrete and Masonry Proceedings of the Third International RILEM Symposium on Demolition and Reuse of Concrete and Masonry held in Odense, Denmark. Organized by RILEM TC 121-DRG and the Danish Building Research Institute. Odense, Denmark 24–27 October 1993 EDITED BY

Erik K.Lauritzen DEMEX Consulting Engineers, Frederiksberg, Denmark

E & EN SPON An Imprint of Chapman & Hall London • Glasgow • New York • Tokyo • Melbourne • Madras

Published by E & FN Spon, an imprint of Chapman & Hall, 2–6 Boundary Row, London SE1 8HN, UK This edition published in the Taylor & Francis e-Library, 2005. “To purchase your own copy of this or any of Taylor & Francis or Routledge's collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.” Chapman & Hall, 2–6 Boundary Row, London SE1 8HN, UK Blackie Academic & Professional, Wester Cleddens Road, Bishopbriggs, Glasgow G64 2NZ, UK Chapman & Hall Inc., One Penn Plaza, 41st Floor, New York NY10119, USA Chapman & Hall Japan, Thomson Publishing Japan, Hirakawacho Nemoto Building, 6F, 1–7–11 Hirakawa-cho, Chiyoda-ku, Tokyo 102, Japan Chapman & Hall Australia, Thomas Nelson Australia, 102 Dodds Street, South Melbourne, Victoria 3205, Australia Chapman & Hall India, R.Seshadri, 32 Second Main Road, CIT East, Madras 600 035, India First edition 1994 © 1994 RILEM ISBN 0-203-62687-7 Master e-book ISBN

ISBN 0-203-63071-8 (Adobe e-Reader Format) ISBN 0 419 18400 7 (Print Edition) 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. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication data available Publisher’s Note This book has been produced from camera ready copy provided by the individual contributors in order to make the book available for the symposium.

Contents

Preface

xii

Introduction

xiv

Organizing Committee

xvi

Scientific Committee

xvi

RILEM Technical Committee 121-DRG

xvii

Sponsors and Cooperating Organizations

xviii

Reports issued by RILEM Technical Committees 37-DRC and 121-DRG

xix

KEYNOTE PAPERS

1 Financial, economical and political aspects of the reuse of construction and demolition waste H.P BARTH

3

2 Guidelines for seismic capacity evaluation of reinforced concrete buildings T.OKADA

9

PART ONE GUIDELINES FOR DEMOLITION WITH RESPECT TO REUSE OF BUILDING MATERIALS

3 Guidelines for demolition with respect to the reuse of building materials: guidelines and experiences in Belgium B.P.SIMONS and F.HENDERIECKX

26

4 Guidelines and experience from the demolition of houses in connection with the Øresund Link between Denmark and Sweden E.K.LAURITZEN and M.JANNERUP

37

PART TWO GUIDELINES FOR THE REUSE OF CONCRETE AND MASONRY AS AGGREGATES IN CONCRETE IN RELATION TO EXISTING SPECIFICATIONS

5 Reuse of demolition materials in relation to specifications in the UK R.J.COLLINS

51

6 Recycling of construction and demolition waste in Belgium: actual situation and future evolution J.VYNCKE and E.ROUSSEAU

60

7 Practical guideline for the use of recycled aggregates in concrete in France and Spain A.MOREL, J.L.GALLIAS, M.BAUCHARD, F.MANA and E.ROUSSEAU

76

8 Concrete/masonry recycling progress in the USA C.J.KIBERT

88

9 Guidelines and the present state of the reuse of demolished concrete in Japan Y.KASAI

97

10 The processing of building rubble as concrete aggregate in Germany R.-R.SCHULZ

114

PART THREE PRESENTATION OF THE WORK DONE BY RILEM TC 121-DRG

11 Report on unified specifications for recycled coarse aggregates for concrete A.HENRICHSEN

129

12 Demolition and reuse following disasters C.DE PAUW

131

PART FOUR RECENT DEVELOPMENTS IN DEMOLITION TECHNIQUES

13 Experience gained in dismantling of the Japan Power Demonstration Reactor (JPDR) M.YOKOTA, Y.SEIKI and H.ISHIKAWA

146

14 Blasting demolition of six-storey reinforced concrete building (Part 1: Experimental blasting of reinforced concrete components) * K.KUROKAWA, T.YOSHIDA, T.SAITO, M.YAMAMOTO and S.NAKAMURA

162

15 Blasting demolition of six-storey reinforced concrete apartment buildings (Part 2: Demolition plan, pre-work measures, collapse conditions) * Y.KASAI, T.SAITO, Y.SEKI, K.TOMITA and J.ISHIBASHI

181

16 Blasting demolition of six-storey reinforced concrete apartment building (Part 3: Blast design, noise and vibration) * I.SAWADA, U.YAMAGUCHI, N.KOBAYASHI, M.NAKAJIKU, H.SHIBATA and T.SHINDO

194

17 Progress of blasting demolition techniques for reinforced concrete constructions in Japan * Y.KASAI, K.HASHIZUME and T.SHINDO

208

18 Fracture control techniques for partial demolition of concrete by blasting * Y.NAKAMURA, S.KUBOTA, J.MUKUGI, T.OHHARA, H.MATSUNAGA and M.YAMAMOTO

221

19 Protection methods from fragmentation in blasting demolition (Part 1: Evaluation of cover materials and protection methods) * K.SUEYOSHI, Y.KASAI, T.SAITOU, K.TOMITA and S.KOBAYASI

235

20 Protection methods from fragmentation in blasting demolition (Part 2: Dynamic movement of fragments) * Y.OGATA, K.KATSUYAMA, Y.WADA, U.YAMAGUCHI, K.HASHIZUME, T.SATO and S.OHTSUBO

251

21 Non-explosive demolition agent in Japan H.HAYASHI, K.SOEDA, T.HIDA and M.KANBAYASHI

267

22 Fast-acting non-explosive demolition agent * K.SOEDA, H.HAYASHI, T.HIDA and K.TSUCHIYA

281

23 Expansive energies of non-explosive demolition agent * H.HANEDA, Y.TSUJI and M.HANADA

296

24 Recent demolition techniques using electric power in Japan W.NAKAGAWA

307

25 The explosive demolition of tall buildings G.T.WILLIAMS

324

26 The application of modified water jets as tools for demolition * A.W.MOMBER

336

27 Investigation into the cutting of bonded prestressing bars during demolition * A.BELHADJ and P.WALDRON

347

PART FIVE PROPERTIES OF CONCRETE WITH RECYCLED AGGREGATES

28 Recycling of concrete in aggressive environment F.R.GOTTFREDSEN and F.THØGERSEN

362

29 Modifying the performance of concrete made with coarse and fine recycled concrete aggregates P.J.WAINWRIGHT, A.TREVORROW, Y.YU and Y.WANG

371

30 Behaviour of reinforced concrete beams containing recycled aggregate F.YAGISHITA, M.SANO and M.YAMADA

384

31 Mechanical and physico-chemical properties of concrete produced with coarse and fine recycled concrete aggregates J.D MERLET and P.PIMIENTA

400

32 Siliceous by-products for use in blended cements * H.H.BAHNASAWY and M.A.SHATER

413

33 The total evaluation of recycled aggregate and recycled concrete * M.KIKUCHI, A.YASUNAGA and K.EHARA

425

34 Physical properties of recycled concrete using recycled coarse aggregate made of concrete with finishing materials * K.YANAGI, M.HISAKA and Y.KASAI

438

35 Exploration of concrete and structural concrete elements made of reused masonry * A.PAKVOR, M.MURAVLJOV and T.KOVACEVIC

453

PART SIX REUSE OF CONCRETE AND MASONRY MATERIALS— EXAMPLES

36 A method for total reutilization of masonry by crushing, burning, shaping 473 and autoclaving H.HANSEN

37 Recycling of clay bricks P.KRISTENSEN

478

38 Special techniques for the recycling of concrete base plates (railway “sleepers”) K.KLÖPPER

482

39 Recycling of reinforced concrete structures and buildings using composite 488 construction: approach to an environmental-economic assessment K.RAHLWES 40 Recycling of concrete for the reconstruction of the concrete pavement on the Vienna-Salzburg motorway H.SOMMER

500

41 Inert wastes from ceramics production and construction works: recycling experiences in Sassuolo, Italy G.F.SAETTI, A.COCCONCELLI, G.FINELLI and C.MEDICI

512

42 Recycling powdered concrete waste * M.SANO, F.YAGISHITA and M.YAMADA

523

PART SEVEN BUILDING WASTE MANAGEMENT

536 43 Development of integrated waste management strategies for demolition waste M.NICOLAI, M.RUCH, Th.SPENGLER, S.VALDIVIA, J.HAMIDOVIC and O.RENTZ 44 Buildings as reservoiers of materials—thier reuse and implications for future construction design T.E.LAHNER and P.H.BRUNNER

548

45 Possibilities for implementing economic, fiscal and practical instruments to promote cleaner technology L.SØBORG

557

46 Transition of the technique of reinforced concrete constructions measured 561 to earthquake damage in Japan K.YAMABE, H.KUBOTA and Y.KASAI

PART EIGHT CLOSING SESSION

47 Retrieving materials—the effects of EC health and safety directives B.S.NEALE

575

48 The Great Belt Link project C.E.LOOSEMORE

582

49 The “Recycled House” in Odense E.BITSCH OLSEN

592

Author index

Subject index

* Papers which are not presented at the symposium or papers which are presented together with other papers.

599

602

Preface The first and second international symposia on Demolition and Recycling of Concrete and Masonry were held in Rotterdam in 1985 and in Tokyo in 1988 under the auspices of RILEM Technical Committee 37-DRC These earlier symposia focused primarily on theoretical aspects of demolition and recycling/reuse of building materials. This work has enabled the necessary knowledge to be built up, but owing to inadequate communication, the knowledge was not being translated into practice. It was therefore decided to follow up the work by TC-37-DRC with recommendations and standards for demolition and reuse of concrete and masonry. This has been the task of the new RILEM TC-121-DRG on Guidelines for demolition and reuse of Concrete and Masonry. The need for demolition, repair and renewal of concrete and masonry structures is rising all over the world. Recent years have demonstrated that numerous natural disasters such as earthquakes and also war activities have caused very extensive damage in urban areas. This has led to a need for effective methods for site clearance and reconstruction. For these reasons the third RILEM symposium deals with subjects concerning the integration of demolition and recycling operations in the construction and housing industry. The aim is to bring together specialist from the construction industry, urban development, disaster mitigation, material scientists, civil engineers and planners to discuss further aspects of demolition and recycling of building materials. The conclusions of the third symposium will be brought in a new RILEM report which is scheduled for completion in 1994. Torben C.Hansen President of RILEM

This page intentionally left blank.

Introduction The Third International RILEM1 Symposium on Demolition and Reuse of Concrete and Masonry follows the first EDA-RILEM symposium, held in Antwerp in 1985, and the second RILEM symposium held in Tokyo in 1988. The Third Symposium concludes the work carried out by two RILEM Technical Committees: TC 37-DRC on Demolition and Reuse of Concrete, 1981–1988, and TC 121DRG on Guidelines for Demolition and Reuse of Concrete and Masonry, 1989– 1993. The Symposium presents world-wide technical developments in the field of demolition and recycling in the last decade. From the work of the TC 37-DRC it could be concluded that there was a lack of increasing technical information, especially guidelines and standards for demolition and recycling of building wastes, in many countries. Furthermore, the need for demolition and repair of concrete structures in the world is rising. In the last decade numerous natural disasters and war activities have caused major damage to urban areas, and this has led to the need for effective methods of site clearance. Therefore RILEM decided to establish TC DRG-121 in 1989 with the main objective of preparing draft guidelines for demolition and reuse of concrete and masonry with special regard to urban development and clearance of urban areas after major natural disasters and wars. At the first meeting of TC DRG-121 in Copenhagen in 1989, it was decided to form two task forces with the following objectives: To prepare technical recommendations leading to guidelines for the production of concrete from recycled concrete and masonry (Task Force 1). To prepare a state-of-the-art report on site clearing, demolition and recycling of damaged concrete structures with special emphasis on earthquake and war damaged structures (Task Force 2). 1

Réunion Internationale des Laboratoires d’Essais et de recherches sur les Matériaux et les Constructions/International Union of Testing and Research Laboratoires for Materials and Structures

Based on recent projects prepared for the EC, based on work in various countries, and based on an official Danish recommendation on recycled aggregates for new concrete, Task Force 1 has prepared a RILEM recommendation on recycled aggregates. In relation to the cooperation between CEN and RILEM, this recommendation will be very valuable

for further standardization in this field. A final report on this subject will be published in 1994. Task Force 2 has collected information on building waste management after recent major natural disasters: e.g. earthquakes in Algeria 1981, Mexico 1985, Armenia 1989, San Francisco 1989, Luzon 1990 and Erzincan 1992. Disaster management and experiences in Japan have been studied in detail. A state-of-the-art report has been prepared with the aim of improving building waste management after natural disasters and wars. These Proceedings contain papers presented at the Third International RILEM Symposium, and also a number of papers which were not presented orally, due to limitations of time. The papers are arranged in the nine sessions of the symposium programme, starting with a keynote session presenting the issues of the symposium. The next two sessions present the state-of-the-art on guidelines for demolition and recycling in different countries throughout the world. The work of RILEM TC 121-DRG and the two Task Forces is then presented in Session 3. In two parallel sessions, 4 and 5, recent developments in demolition techniques and recycling are covered, followed by a presentation of practical experience and examples in Session 6. Other aspects of demolition and recycling (e.g. management, legal and economic aspects) are dealt with in Session 7, and the symposium concludes with the presentation of two major recycling projects in Denmark. As chairman of RILEM TC 121-DRG I sincerely hope that the symposium will be successful and will contribute to a better understanding and further development of techniques for demolition and recycling of concrete and masonry. I would like to thank everyone who served as members and corresponding members of RILEM TC 121-DRG. Especially, I thank the Secretary Mr Johan Vyncke (B); the Chairman of Task Force 1, Mr Anders Henrichsen (DK): the Chairman of Task Force 2, Mr Carlo de Pauw (B); and all members of the two Task Forces for their enthuiasm and hard work. Moreover, I would also like to express my thanks to the Chairman of the Organizing Committee, Dr Bjarne Chr. Jensen; the Secretary of the Organizing Committee, Mr Jens Chr. Ellum; and the members of the Organizing Committee and the Scientific Committee for all their work in connection with the preparation of this symposium. Very special thanks go to RILEM and the cooperating organizations, and to the Danish Building Research Institute for organizing this symposium. Erik K.Lauritzen

Organizing Committee Dr Bjarne Chr. Jensen, Professor h.c., Chairman, Carl Bro A/S Denmark Mr Erik K.Lauritzen, Coordinator, DEMEX Consulting Engineers A/S, Denmark Mr Jens Chr. Ellum, Secretary, Danish Building Research Institute, Denmark Mr Michel Brusin, General Secretariat, RILEM, France Mr Georg Christensen, Danish Building Research Institute, Denmark Mr Carlo De Pauw, ENBRI, Belgian Building Research Institute, Belgium Mr Niels Jørn Hahn, R98, Copenhagen, Denmark Mr Anders Henrichsen, Professor h.c., Dansk Beton Teknik A/S, Denmark

Scientific Committee Mr Erik K.Lauritzen, Chairman, DEMEX Consulting Engineers A/S, Denmark Dr Susi Buchner, Gifford and Partners, England Mr Carlo de Pauw, Belgian Building Research Institute, Belgium Dr Charles Hendriks, Professor, INTRON B.V., The Netherlands Mr Anders Henrichsen, Professor h.c., Dansk Beton Teknik A/S, Denmark Dr Yoshio Kasai, Professor, Nihon University, Japan Dr Peter Lindsell, Gifford and Partners, England Dr Christer Molin, Tremix, Sweden Dr André Morel, CEBTP, France Mr Torsten Thorsen, Danmarks Ingeniørakademi, Denmark Dr Tony Trevorrow, Nottingham Trent University, England Mr Johan Vyncke, Belgian Building Research Institute, Belgium Dr Peter J.Wainwright, University of Leeds, England

RILEM Technical Committee 121-DRG Mr Erik K.Lauritzen, Chairman, DEMEX Consulting Engineers A/S, Denmark Mr Robert Basart*, European Demolition Association, The Netherlands Dr Susi Buchner, Gifford and Partners, England Mrs Catherine Charlot-Valdieu*, CSTB, France Mr Carlo de Pauw, Belgian Building Research Institute, Belgium Dr Torben C.Hansen, Professor*, Technical University of Denmark Dr Charles Hendriks, Professor, INTRON B.V., The Netherlands Mr Anders Henrichsen, Professor h.c., Dansk Beton Teknik A/S, Denmark Dr Yoshio Kasai, Professor, Nihon University, Japan Mr Joseph F.Lamond, ACI 555, USA Dr Peter Lindsell, Gifford and Partners, England Mr Terence R.Mills*, England Dr Christer Molin, Tremix, Sweden Dr André Morel, CEBTP, France Dr Mike Mulheron*, University of Surrey, England Dr Rolf-Rainer Schulz*, Fachhochschule Frankfurt a.m., Germany Mr Torsten Thorsen, Danmarks Ingeniørakademi, Denmark Dr Tony Trevorrow, Nottingham Trent University, England Mr Johan Vyncke, Secretary, Belgian Building Research Institute, Belgium Dr Peter J.Wainwright, University of Leeds, England Mr Myles Whelan, Whelan the Wrecker Pty Ltd, Australia * Corresponding member

Sponsors and Cooperating Organizations The Symposium has been sponsored by RILEM

Réunion Internationale des Laboratoires d’Essais et de Recherches sur les Matériaux et les Construction, International Union of Testing and Research Laboratories for Materials and Structures in cooperation with

UNESCO United Nations Educational, Scientific and Cultural Organization ACI

American Concrete Institute

ISWA

International Solid Waste Association

DBF

Danish Concrete Association

ENBRI

European Network of Building Research Institutes

CIB

Conseil International du Bâtiment

IDNDR

International Decade of Natural Disaster Reduction

UNCRD

UN Center for Regional Development

DBV

Deutscher Beton-Verein E.V.

Reports issued by RILEM Technical Committees 37-DRC and 121-DRG [1] EDA-RILEM (1985). Demolition Techniques. Proceedings of the First International EDA-RILEM Conference on Demolition and Reuse of Concrete, Rotterdam, 1–3 June, 1985, European Demolition Association, Wassenaarseweg 80, 2596 CZ Den Haag, The Netherlands. [2] EDA-RILEM (1985). Reuse of Concrete and Brick Materials. Proceedings of the First International EDA-RILEM Conference on Demolition and Reuse of Concrete, Rotterdam, 1–3 June, 1985, European Demolition Association, Wassenaarseweg 80, 2596 CZ Den Haag, The Netherlands. [3] Y.Kasai (Editor) (1988). Demolition and Reuse of Concrete and Masonry Volume One: Demolition Methods and Practice Volume Two: Reuse of Demolition Waste Proceedings of the Second International RILEM Conference on Demolition and Reuse of Concrete, Tokyo, 7–11 November 1988, Chapman & Hall, London. [4] Torben C.Hansen (Editor) (1992). Recycling of Demolished Concrete and Masonry, Third state-of-the-art report 1945–1989, RILEM Report No. 6, E. & F.N.Spon, London. [5] Erik K.Lauritzen (Editor) (1993). Demolition and Reuse of Concrete and Masonry. Proceedings of the Third International RILEM Conference on Demolition and Reuse of Concrete and Masonry, Odense, Denmark, 24–27 October 1993, E. & F.N.Spon, Chapman & Hall, London. Planned issues: [6] Anders Henrichsen, Charles Hendriks, Johan Vyncke (1993), Guidelines for Reuse of Concrete and Masonry Rubble as Aggregates in Concrete, RILEM TC-121-DRG, Task Force 1 Report. Draft report will be available at the RILEM Symposium, October 1993. Final report is planned to be published as RILEM Technical Recommendation in RILEM “Materials and Structures” in 1994. [7] Johan Vyncke, Y.Kasai, Carlo De Pauw, Erik K.Lauritzen, Susi Buchner (1993) Demolition of Structures and Reuse of Buildings and Construction Material following Disasters, RILEM TC-121-DRG, Task Force 2 Report, E. & F.N.Spon, Chapman & Hall, London.

KEYNOTE PAPERS

This page intentionally left blank.

1 FINANCIAL, ECONOMICAL AND POLITICAL ASPECTS OF THE REUSE OF CONSTRUCTION AND DEMOLITION WASTE H.P BARTH European Construction Industry Federation (FIEC), Brussels, Belgium, Federation of Dutch Contractors Organisations (AVBB), The Hague, The Netherlands Demolition and Reuse of Concrete. Edited by Erik K.Lauritzen. © 1994 RILEM. Published by E & FN Spon, 2–6 Boundary Row, London SE1 8HN. ISBN 0 419 18400 7. Abstract Reuse of construction and demolition wastes forms part of a far wider, complex issue, primarily relating to supplies of construction materials. Within this area, environmental requirements demand objectives for optimizing the use of secondary materials. The realisation of these objectives will be feasible only if both legislation and the markets—in which principals play a crucial role—allow scope and/or create the right conditions for this. Only through the combined efforts of all parties in the market can these objectives be attained. An integrated and consistent policy is needed on the use of secondary raw materials, with clear minimum requirements which are binding on all market parties. Standardization plays a crucial role here. Legislation should be clear, unambiguous, workable and feasible. Cost-benefit analyses should be prepared for all policy measures, including consideration of their environmental effectiveness, their impact on industrial competitiveness and the fair distribution of responsibilities and costs. Existing EC-legislation does not satisfy any of these considerations and criteria. Key words: Legislation, regulation, policy, economic feasibility, financial feasibility, principals, construction industry, market, standardization.

1 Introduction The main objective of construction contractors is to create construction products which

Demolition and reuse of concrete and masonry

4

offer good quality and price-performance in all respects. A prime requirement for this is the availability of good quality, inexpensive construction materials. Whether these are primary or secondary materials is of lesser importance: the two compete with each other. The construction industry is served by the availability of secondary raw materials of reliable quality, at favourable prices. Firstly, this will allow the construction industry to help reduce the waste problem and so fulfil its social responsibility for a healthy environment. Furthermore, environmental considerations threaten to create shortages of scarce and expensive primary raw materials. Dumping or incineration of construction and demolition wastes (including dredging sludge and soil) also creates environmental problems and is, moreover, very expensive. Finally, secondary materials already play an important role in the public works and civil engineering sector; the unavailability of cheap, good quality secondary materials would force these sectors to resort to costly primary raw materials. The construction industry can itself contribute towards the availability of good quality, inexpensive secondary raw materials by introducing measures which allow segregation and reutilization of construction and demolition waste. The construction industry has its own, independent responsibility in this respect. However, the opportunities for optimising separate collection and removal to reprocessing facilities are largely determined at earlier stages of the construction process, in which principals, architects and suppliers also play a role. Moreover, adequate processing capacity and application possibilities must be available at later stages of the construction process. These can be created only through clear legislation, applying to all parties in the market. In addition to construction and demolition wastes, secondary materials are also produced from industrial residues. The construction industry has no influence on the availability of these residues, but can affect their application. Again, the market and legislation determine the scope for optimizing applications. The various aspects of this subject are closely interrelated, or should be so. If construction companies do not collect construction and demolition waste separately and remove it for reprocessing, a shortage of the necessary secondary raw materials will be created. If the application of secondary materials is hampered by market forces or legislation, a vast quantity of unusable waste materials will result, with all the attendant costs and environmental problems. What does the construction industry want? Construction industry is calling for clear and consistent legislation, with minimum requirements for compulsory application of recycled materials by all market parties, but in particular, by principals and architects. This requires additional, serviceable regulations and requirements, in areas including segregated collection, training and standardization. However, the emphasis should continue to lie on optimizing possibilities for recycling and application. So far, legislation has focused purely on the supply side—on producers/demolition companies, transporters and waste collectors/managers—at the European Community (EC) level, but also in the various Member-States. The demand side (principals and architects) has been ignored. In fact, construction and environmental legislation sets such stringent requirements for the application of construction materials that optimal application of secondary raw materials is being thwarted. This legislation only increases the existing confusion and mistrust among principals and architects with regard to

Financial, economical and political aspects

5

secondary raw materials. 2 Problems for optimal recycling This brings us to the bottlenecks in policy and legislation which stand in the way of optimal application of secondary materials. Policy and legislation on reuse of secondary materials do not consider the recovery and supply of primary materials. As long as primary materials are available in generous quantities at competitive prices, there will be no question of optimal reuse of secondary materials. This will be reinforced by problems relating to market acceptance of secondary materials. There is confusion and prejudice among all parties regarding environmental hygiene and construction technology aspects, as well as the costs of secondary materials. Demand for these materials is consequently far from optimal. Both points are reflected in the position of the construction industry. Construction contractors are wary of distortion of competition. The availability of cheap primary raw materials, coupled with limited market acceptance of secondary materials, means that contractors will think three times before applying the latter. After all, competitors who simply work with primary materials will, in many cases, receive preferential treatment from principals, at the expense of the progressive, environmentally-conscious contractor. If we genuinely want to achieve optimal use of secondary materials, measures must be introduced in the areas of material supply, construction regulations, education and consciousness-raising and in the transportation and processing of construction and demolition waste. 3 Policy and legislation: the ideal situation A sound policy on recycling of construction and demolition wastes, or on secondary raw materials in general, will cover all aspects and all parties in the market. If the European Commission wants to encourage recycling, it will have to draw up regulations relating to recovery and supply of raw materials, the construction process, training and consciousness-raising, (quality) standardization and certification, segregated collection and removal, and treatment capacity (including in licensing procedures). The requirements of sound policy go still further. After all, it is not only construction and demolition waste that is at issue, but also industrial residues. In this respect, government authorities should set requirements for design and manufacturing regulations, in order to realise good quality, environmentally sound materials. Furthermore, international harmonisation of this legislation will be necessary. If one country reduces recovery of raw materials while imports of these materials from another country increase, or if a country announces a ban on dumping of construction and demolition waste when dumping is permitted 5 kilometres away across the national border, policy cannot succeed. Sound policy must therefore be clear, unambiguous, workable and feasible, consistent,

Demolition and reuse of concrete and masonry

6

based on reliable data and a thorough cost-benefits analysis, and must apply to all market parties for the longer term. Policies such as those described above are non-existent at present. At both the EC and the national level, policy and legislation focus one-sidedly on segregation and disposal of wastes. 4 Policy and legislation: the present situation The following outline of current policy is based on EC policy. The differences in policy and legislation between the different member states are so great that they cannot be classified under one heading. This brings us to the first problem. The approach chosen by the EC is based purely on environmental hygiene. Construction and demolition waste can give rise to environmental problems. The character and severity of these problems will depend on many different factors (the amount and composition of waste, construction culture, landscape and space, existing disposal structures), and will therefore vary from one country to another. Even the objective need for legislation on environmental aspects of construction and demolition waste is different for each country. This shows that a purely environmental approach will be inadequate. Another angle must therefore the chosen, producing more common points of departure; that of construction regulations and of raw material supply. With regard to construction regulations, it should be noted that the use of secondary raw materials is not prescribed in the Directive on Construction Products. There is no question of a policy on recovery of primary raw materials. All attention focuses on waste management. Waste management is one of the main themes of the European Commission’s environmental policy, as laid down in the Community Strategy for Waste Management (1989), the Council Resolution on Waste Management (1990), the Fifth Environmental Action Programme (1992) and in five Directives. In the first Directives, dating from the 1975–1986 period, the approach was based purely on environmental hygiene, the objective being ‘the protection of human health and the environment against harmful effects caused by the collection, sorting, transport, treatment, storage and disposal of waste and by the transformation operations necessary for its reuse, recovery and recycling.’ The more recent Directives (from 1991) already place more emphasis, at least in words, on recycling and reuse as ends in themselves, and urge the Member-States to take steps to increase market opportunities for sales of recycled materials. This call is often confined to the preambles of the Directives. Real commitments are not mentioned. The most striking example of this one-sided approach is found in the Directive on Civil Liability for Damage caused by Waste. This refers solely to waste removal and collection agencies. Reuse is not mentioned, while it is precisely in this area that clarity is needed on responsibilities and liability. In short, EC legislation focuses one-sidedly on the creation, removal, collection and storage of construction and demolition waste, as an isolated issue. There is no question of an integrated approach to optimal recycling applications.

Financial, economical and political aspects

7

5 The EC Construction and Demolition Waste Project Group The construction industry hoped that this situation would change with the formation, at the end of 1992, of the EC Construction and Demolition Waste Project Group, in which all Member-States and all market parties are represented, as well as the European Commission. This EC Project Group must be seen in the light of the new strategy in EC waste policy. Since 1991, the European Commission has adopted an entirely new approach to the field of waste management. Instead of completely independent formulation of policy and legislation, the EC has decided to involve the Member-States and the relevant groups in society, in the hope that this will speed up the legislative process and, more importantly, make legislation more acceptable in the market. The launch document for the project group states that its intention is ‘to turn the waste problem from an environmental problem into a source of raw materials with a positive economic and social value.’ Another principle is ‘to find environmentally-friendly solutions as far as possible ahead of the waste stage.’ These are fine words, but what do they mean in practice? Firstly, the representatives of the principals and architects did not attend the first two meetings. Secondly, these meetings discussed only the classification of waste flows and reduction targets for prevention and reuse. No attention was paid to problems in the market, to standardization or to the recovery of primary raw materials. Furthermore, the EC has just published a European Waste Catalogue. Regrettably, this must once again be described as a one-sided and incomplete document. It gives a rough indication of whether a material is hazardous or non-hazardous, which in itself does not say much and offers no leads for principals or architects—only for managers of tips and incineration plants. In fact, this approach only increases the doubts and confusion among potential appliers, and hampers reuse. However, private sector organisations such as RILEM are taking valuable initiatives in the areas of standardization, certification, increasing application possibilities by including stipulations in standard specifications etc. The EC and other government authorities should focus more closely on this sort of development and adopt or include the results in concrete policy and legislation, in order to optimise reuse. The construction industry, organised at the European level in FIEC, will continue to draw attention to this in its contacts with the European Commission and through its membership of CEN. 6 Conclusion Reuse of construction and demolition waste forms part of a much wider, complex issue— that of raw material supplies in the construction industry—and can only be solved with the effort and conviction of all market parties concerned. It is pointless to pick out one aspect or sector, and to make this the focus of all attention or criticism. Only through an integrated approach, and through the efforts of all market parties

Demolition and reuse of concrete and masonry

8

concerned, can the objectives of reuse be realised. Within this approach, framework legislation must be drawn up, with clear and unambiguous minimum requirements on the use of secondary raw materials, with which all parties in the market must comply. Cost-benefit analyses should be made for all measures, covering their environmental effectiveness, their effects on pubic and private expenditure (market acceptance), their impact on industrial competitiveness and the fair distribution of responsibilities and costs. Finally, government and semi-government agencies should make use of the valuable knowledge and insights being developed in many organisations, including RILEM. If we want companies to contribute to the optimal reuse of construction and demolition waste in an environmentally and economically sound manner, certain conditions much be met: 1. Broad market acceptance, which includes adequate public and private expenditure and investment; 2. Clear, harmonized and feasible regulations; 3. Dialogue and cooperation, both between the construction industry and the authorities, and within each of these sectors; 4. A constructive, forward-looking attitude on the part of the construction industry itself. A general condition, that encompasses all others and which must absolutely be taken into consideration when any environmental measure is contemplated, is that ‘care for the environment and environmental measures should not endanger the continuity of construction activities and the competitiveness of individual companies.’

2 GUIDELINES FOR SEISMIC CAPACITY EVALUATION OF REINFORCED CONCRETE BUILDINGS T.OKADA Institute of Industrial Science, University of Tokyo, Tokyo, Japan Demolition and Reuse of Concrete. Edited by Erik K.Lauritzen. © 1994 RILEM. Published by E & FN Spon, 2–6 Boundary Row, London SE1 8HN. ISBN 0 419 18400 7. Abstract For the rehabilitation of existing buildings, it is necessary to evaluate the structural capacity before and after rehabilitation. In this paper, the basic concept of the guideline to evaluate the seismic capacity of existing reinforced concrete buildings, the guideline for seismic strengthening and their application to existing buildings in Japan are described. The decision criteria to screen vulnerable buildings is also described. Keywords: Seismic Capacity Evaluation, Reinforced concrete, Building, Seismic Strength, Ductility, Rehabilitation

1 Introduction A rehabilitation of buildings has been made mostly when buildings, building components, or materials were physically deteriorated with age. However, there is a trend to rehabilitate rather new buildings. For example, the recent development of the earthquake engineering requires that the seismic safety of existing buildings must be reevaluated and increased, if necessary. To increase the seismic safety, the structural rehabilitation; strengthening, is necessary. Another example is the rehabilitation due to the change of the use of the building. The reform of the educational system, which is a recent trend in Japan, is requiring the remodel of existing school buildings associated with structural renovation. These non-physical reasons could be called “deterioration of software”, while the physical reasons “deterioration of hardware”. A large number of reinforced concrete buildings have been designed and constructed in Japan since 1920’s according to the seismic codes requiring rather high level of seismic capacity. However, the recent experience of earthquake damage and the current knowledge in earthquake engineering suggest that some of the existing buildings do not

Demolition and reuse of concrete and masonry

10

have sufficient seismic capacity. Since 1968 Tokachi-Oki Earthquake, the importance to develop the methodology to evaluate seismic capacity of existing buildings, as well as to revise the existing seismic codes, had been strongly recognized, and various methodologies were proposed [(1), (2), (3)]. In order to unify them, the guideline for evaluation of seismic capacity of existing reinforced concrete buildings [(4)] was developed in 1977 by the special committee at the Japan Building Disaster Prevention Association under the sponsorship of the Ministry of Construction, Japanese Government. The author was the chairman of the task committee to draft the guideline. The guideline for strengthening of existing buildings estimated vulnerable by the evaluation guideline was also developed [(5)]. The guidelines have been widely used and applied to many existing buildings. And they have also been used for estimating reserve seismic capacity of earthquake damaged buildings. The purpose of this paper is to describe 1) basic concept of the gruideline to evaluate seismic capacity, 2) seismic capacity of buildings damaged due to past severe earthquakes, 3) seismic capacity of existing buildings, 4) decision criteria to screen sound buildings and to strengthen vulnerable buildings and basic concept to strengthen vulnerable buildings. 2 Basic Concept of The Guideline for Seismic Capacity Evaluation of Existing Reinforced Concrete Buildings The guideline can be used to evaluate the seismic capacity of existing reinforced concrete buildings and consists of three different level procedures; first, second and third level procedures. The first level procedure is the simplest, but most conservative of the three, while the basic concept is common for all three. In the guideline, the unified seismic performance index of structure (Is) up to six stories is evaluated by the following equation at each story and to each direction; Is=Eo·G·SD·T where, Eo = basic structural index calculated by ultimate horizontal strength, ductility, number of stories and story level considered. At the first story, the Eo-index is basically estimated by: Eo=(Ultimate Based Shear Coefficient)×(Ductility) G = local geological index to modify the Eo-index. SD = structural design index to modify the Eo-index due to the grade of the irregularity of the building shape and distribution of stiffness. T

= time index to modify the Eo-index due to the grade of the deterioration of strength and ductility.

The standard values of the G-, SD- and T-indices are 1.0. The Is-index corresponds to the level of response acceleration normalized by the gravity which causes damage to the building. Therefore, the building can be

Guidelines for seismic capacity evaluation of reinforced concrete buildings

11

approximately judged whether it is safe or not according to the earthquake level expected at the building site and the fundamental period of the building. In order to calculate the Is-index, any of the first, the second and the third level screening procedure may be used. i) The First Level Screening Procedure Eo-index is approximately calculated from the horizontal strength of the building, based on the sum of the horizontal cross sectional areas of columns and walls and on their average unit strength. SD-index is evaluated by the eight items on the shape of the building both in plan and section. T-index is evaluated, based on the age of the building and the visible distortion and cracks in columns and walls. ii) The Second Level Procedure Eo-index is calculated by the ultimate horizontal strength, failure modes and ductility of columns and walls with assumption of rigid and strong beam and floor system. SD-index is evaluated by horizontal stiffness distribution and vertical mass and stiffness distribution in addition to the results in the first level evaluation procedure. T-index is evaluated by the grade of structural cracking, distortion, changes in quality and deterioration of the building. iii) The Third Level Procedure Eo-index is calculated by the ultimate horizontal strength, failure modes and ductility of columns and walls, based on failure mechanism of frames, considering the strength of beams and overturning of walls. SD-index and T-index may be taken as the same values as used in the second level screening procedure. 3 Seismic Capacity of Earthquake Damaged Buildings An example of the damage ratio of low-rise reinforced concrete buildings due to past severe earthquake in Japan is shown in Table 1. Most of them were three to four story buildings. The damage ratio including heavy and medium damage in the intensity VIII– IX zone by the modified Mercalli scale was about 10% in each earthquake and the ratio of heavy damage was less than 5% [(6)]. These ratios were same in other earthquakes[(7), (8)]. In order to estimate their seismic capacity, the Is-indices were calculated by the guideline as shown in Fig. 1. In the Fig. 1, the Is-indices of thirty reinforced concrete buildings subjected to 1968 Tokachi-Oki Earthquake, 1978 Miyagi-ken-Oki Earthquake and 1978 Izuoshima-Kinkai Earthquake are shown [(9)]. The abscissa expresses the Is-indices of the east to west direction of the buildings and the ordinate the Is-indices of the north to south direction. Numerals show ID-numbers of the buildings and a couple of points connected by broken line shows upper and lower bounds of the Is-index of the bullding. The buildings with Is-

Demolition and reuse of concrete and masonry

12

index of more than 0.6 by the second level screening procedure were not damaged and most of the buildings with Is-index of less than 0.4 were damaged. A similar trial was done for the buildings in the city of Mexico which experienced the 1985.9.19–20 Mexico Earthquake as shown in Fig. 2. Seismic capacities of seven types of apartment houses at Tlaltelolco, two college buildings, two secondary school buildings and an office building were evaluated by the evaluation standard [(10)]. According to increase of the Is-indices, the number of damaged buildings decreases and Is-index of about 0.4 is a border between damage and non-damage.

Fig. 1 IS-indices by Second Level Screening Procedure vs. Earthquake Damage In Japan [Ref. (9)]

Guidelines for seismic capacity evaluation of reinforced concrete buildings

Fig. 2 IS-indices by Second Level Screening Procedure vs. Earthquake Damage in Mexico [Ref. (10)]

13

Demolition and reuse of concrete and masonry

Fig. 3 Distribution of IS-indices of Existing-Buildings [Ref. (9)]

Fig. 4 Distribution of IS-indices [Ref. (11)]

14

Guidelines for seismic capacity evaluation of reinforced concrete buildings

15

Fig. 5 Distribution of ET-indices [Ref. (11)]

4 Seismic Capacity of Existing Buildings Since the guideline was published, much effort to apply it to existing buildings and to find out vulnerable buildings has been done by Japanese engineers. For an example, in Shizuoka Prefecture where a severe earthquake is predicted to occur in near future, the guideline has been applied to more than four thousand public buildings and about four hundreds of them have already been strengthened or demolished. Fig. 3 shows the distribution of seismic capacity of about 700 existing buildings in Shizuoka Prefecture, where the Is-indices to both directions of each building are considered [(11)]. Most of them were designed and constructed before the code revision in 1970. As shown in the figure, the distribution of the Is-indices can be approximated by a log-normal probability density function. By the guideline, the building with enough seismic capacity is screened by the equation (1). Is≥ET

(1)

The ET-index expresses the decision criteria depending upon the level of ground acceleration, soil condition, number of stories and type of failure [(9), (11)]. An example of the ET-index In the lowest seismic zone in Shizuoka Prefecture is shown in Table 2, where the input acceleration to the basement of building on 0.4 sec. ground soil is

Demolition and reuse of concrete and masonry

16

assumed as 23% of the gravity (0.23g). The acceleration in the highest seismic zone is double of that in the lowest zone. The ET-index was determined by the consideration of non-linear earthquake response of the idealized structural models and the damage experience. For the different level of the ground acceleration, the ET-index is considered proportional to the ground acceleration. 5 Decision Criteria for Screening and for Strengthening Vulnerable Buildings The building satisfying the equation (1) may avoid a damage. However, even if the equation (1) is not satisfied, it does not always mean the building must be strengthened. Because, the equation (1) is considered to give an enough condition to judge the safety of the building. Fig. 1 shows such tendency well. If all buildings with Is-indices less than ET-indices were unsafe, the damage ratios In past earthquakes would be greater than the ratios shown in Table 1. Therefore, a different decision criteria should be used for strengthening. Table 3 shows the decision criteria for strengthening proposed for school buildings [(12)]. In order to verify the concept used in the criteria in Table 3, a reliability based analysis on the seismic safety of existing buildings and damaged buildings was done. Fig. 4 is a schematic expression of distribution of the Is-indices of existing and damaged buildings. Fig. 4-(a) is showing the distribution when the ET-index is deterministic, while Fig. 4-(b) is showing the probabilistic characteristics of ET-index. The hatched part in the Fig. 3 shows the histogram of

Table 1 Damage Ratio due to 1978 Miygi-ken-Oki Earthquake [Ref. (6)]

Guidelines for seismic capacity evaluation of reinforced concrete buildings

Table 2 ET-indices for Maximum Ground Acceleration of 0.23g [Ref. (9)]

Table 3 Decision Criteria for Strengthening of School Buildings [Ref. (10)]

17

Demolition and reuse of concrete and masonry

Fig. 6 Concepts of Seismic Strengthening [Ref. (13)]

Fig. 7 Strengthening by Walls or Braces [Ref. (5)]

18

Guidelines for seismic capacity evaluation of reinforced concrete buildings

Fig. 8 Detail to provide R/C Wall in Existing Frame [Ref. (13)]

Fig. 9 Detail of Connection between Wall and Existing Frame [Ref. (13)]

19

Demolition and reuse of concrete and masonry

20

Fig. 10 Detail of Steel Brace for Strengthening of Existing R/C Frame [Ref. (13)]

the Is-indices of damaged buildings shown in Fig. 1, where a modification is employed so that the number of the damaged buildings becomes 10% of the total number of buildings. The shape of the Fig. 3 is similar to Fig. 4-(b). It suggests the ET-index may be considered to be probabilistic. Defining P1 and PET which represent density functions of Is-index of existing buildings and ET-index, respectively, the damage ratio V is determined by

(2) Setting

(3) The term of Vp2 may be considered to represent the frequency of Isindices of damaged buildings shown in Fig. 3. Substituting the function p1 in Fig. 3 and the density of hatched part In Fig. 3 Into the equation (3), we obtain the probabilistic density of ETindices as shown in Fig. 5. Assuming the normal distribution, we obtain the probabilistic density function of ETindices as shown in Fig. 5 The curve

in Fig. 3 is obtained by the equation (3), where

Guidelines for seismic capacity evaluation of reinforced concrete buildings

21

p1 function in Fig 3, and pET function in Fig. 5 are used.

Fig. 11 Strengthening of Columns to Increase Ductility [Ref. (5)]

6 Basic Concept for Strengthening of Vulnerable Buildings A building judged that strengthening is necessary should be strengthened as soon as possible to prevent earthquake damage even if it has not experienced severe earthquake. A vulnerable building lacks enough strength or enough ductility or sometimes both of them. Therefore, the purpose of strengthening is to provide (1) additional strength, (2) additional ductility or (3) both additional strength and ductility. These concepts are illustrated in Fig. 6. Most popular method to increase strength is to provide reinforced concrete shear walls or steel braced frames into existing framing system as shown in Fig. 7. As shown in Fig. 8, anchor bolts are provided at the existing beams and columns, wall reinforcing bars provided and then, concrete is cast. In order to prevent a splitting shear failure at the connection of wall and frame, spiral reinforcement is often used. Special grouting is also used at the connection as shown in Fig. 9. When the soil condition is not so good, the steel braced frame is sometimes used to minimize the increase of the building weight and to increase the strength as shown in Fig. 10. In order to increase the ductility of the building, various techniques to enclose existing column by steel plate or by reinforced concrete jacketing have been developed as shown in Fig. 11. Gaps are

Demolition and reuse of concrete and masonry

22

usually provided both at the top and the bottom of the column, to prevent the increase of bending capacity and to increase only the shear capacity, which is expected to increase ductility. 7 Concluding Remarks Evaluation of seismic capacity of existing buildings and the strengthening if necessary are very important to mitigate earthquake hazard. In this paper, recent trends on this problem in Japan are reported. The author wishes the methodologies described here is applied to the existing buildings not only in Japan but also in other countries with a proper modification. 8 References (1) Hirosawa, M. (1973), Proposal on Standard to Judge Seismic Capacity of Existing R/C Buildings, Kenchiku Gijutsu (in Japanese). (2) Architectural Institute of Japan (1975), Method to Evaluate Seismic Safety of R/C School Buildings and Method of Strengthening (in Japanese). (3) Okada, T. and Bresler, B. (1976), Strength and Ductility Evaluation of Low-Rise Reinforced Concrete Buildings-Screening Method-, EERC Report No.76–1, Univ. of California, Berkeley. (4) Japan Building Disaster Prevention Association (1977), Guideline for Evaluation of Seismic Capacity of Existing Reinforced Concrete Buildings (in Japanese). (5) Japan Building Disaster Prevention Association (1977), Guideline for Strengthening of Existing Reinforced Concrete Buildings (in Japanese). (6) Architectural Institute of Japan (1980), Report on Damage due to 1978 Miyagi-kenOki Earthquake (In Japanese). (7) Building Research Institute (1965), Damage on Buildings due to 1964 Niigata Earthquake, Report of Building Research Institute, No.42 (in Japanese). (8) Architectural Institute of Japan (1968), Report on Damage due to 1968 Tokachi-Oki Earthquake (in Japanese). (9) Umemura, H., Okada, T. and Murakami, M. (1980), Seismic Judgment Index Values for Guideline for Evaluation of Seismic Capacity of R/C Buildings, Proceedings of Annual Convention of Architectural Institute of Japan (in Japanese). (10) Okada, T. et al. (1986), Seismic Capacity of Reinforced Concrete Buildings which suffered 1985 Mexico Earthquake in Mexico City, Part 1–part 13, Proceedings of the Annual Convention of Architectural Institute of Japan (in Japanese). (11) Okada, T. (1983), Seismic Capacity and Strengthening of Reinforced Concrete Buildings, Proceedings of Panel Discussion for Strengthening of Existing Reinforced Concrete Buildings, Japan Concrete Institute (in Japanese). (12) Murakami, M. and Okada, T. (1981), Evaluation and Judgment of Seismic Safety of R/C School Buildings, Japan Building Disaster Prevention Association (in Japanese). (13) Japan Concrete Institute (1984), Handbook for Strengthening of Concrete Structures, Editor: T.Okada, Gihodo-Shuppan.

PART ONE GUIDELINES FOR DEMOLITION WITH RESPECT TO REUSE OF BUILDING MATERIALS

3 GUIDELINES FOR DEMOLITION WITH RESPECT TO THE REUSE OF BUILDING MATERIALS: GUIDELINES AND EXPERIENCES IN BELGIUM B.P.SIMONS and F.HENDERIECKX Belgian Building Research Institute, Zarentem, Belgium Demolition and Reuse of Concrete. Edited by Erik K.Lauritzen. © 1994 RILEM. Published by E & FN Spon, 26 Boundary Row, London SE1 8HN. ISBN 0 419 18400 7. Abstract Demolition guidelines can constitute a powerful tool to improve the quality of the waste and to raise the quantity of the recyclable fraction. However, demolition guidelines are only effective if they, being one tool in a global concept for the stimulation of the recycling of construction and demolition waste, can act in synergy with other initiatives. Demolition is treated with respect to requirements of the final products, leading to specifications for the waste. In this frame work, concepts for demolition guidelines are presented. Keywords: Construction and demolition waste, Demolition, Incentives, Demolition guidelines.

1 Introduction In Western Europe, the yearly amount of construction and demolition waste, is about 0,7 to 1 ton per inhabitant. This is nearly twice the weight of the municipal solid waste. Far the biggest part of this construction and demolition waste is good recyclable, at least, if it is brought into a recycling installation in a good condition, considering the requirements of the recycled products. This is only possible, if in demolition practice these aspects are sufficiently taken in account. Demolition guidelines can constitute a powerful tool to improve the quality of the waste and to raise the quantity of the recyclable fraction. However, demolition guidelines are only effective if they, being one tool in a global concept for the stimulation of the recycling of construction and demolition waste, can act in synergy with other initiatives. (1)

Guidelines for demolition with respect to the reuse of building materials

27

2 Demolition guidelines as part of a global concept for the stimulation of the reuse of construction and demolition waste: 2.1 Materials and waste streams A global concept for the stimulation of the reuse of construction and demolition waste starts with a clear insight in the waste streams (scheme 1) and in the mechanisms, who steer these streams. The waste is generated during construction, renovation and demolition of roads, buildings,… It’s transported to recycling installations, on site or centralised (sometimes via a separation installation), or to landfill or, in some cases to an incinerator. The use of recycled aggregates in construction works closes the circle. Scheme 1 material and waste streams

Demolition and reuse of concrete and masonry

28

2.2 Estimated quantities in Belgium Belgium is turning into a federal country, more and more competencies are transferred from the federal level to the three regions: Flanders, Brussels and Wallonia. Environmental as well as infrastructural competencies are regionalised; in other words, the three regions develop their own policy and their own instruments in these issues. Therefore, the 3 regions are treated separately in this article.

Guidelines for demolition with respect to the reuse of building materials

29

2.2.1 Quantities of wastes in the Flanders region (2) In a recent study, the amount of construction and demolition wastes in Flanders was estimated at ca 4.6 million tons per year (graph 1). Some 40% consists of concrete while some other 40% of masonry; the remaining 20% consists of bituminous materials (12%), ceramics (3.4%) and various wastes.

The sources of the wastes are buildings (residential or not), roads and building material manufacturing companies (graph 2).

2.2.2 Quantities in the Brussels region (3)

Demolition and reuse of concrete and masonry

30

In the Brussels region, a similar study was carried out. The amount was estimated at 850 000 to 1 000 000 tons per year. The sources and the composition are given in graphs 3 and 4

In comparison to Flanders, the non residential buildings take a far bigger share (graph. 4) (51.9 vs 44.5%). On the other hand, the most important difference in average composition is a higher amount of masonry (45% vs 40%).

2.2.3 Quantities in the Walloon region Extrapolation of the figures from Flanders and Brussels, to the Walloon part of the country, would allow to estimate the amount to some 2 million tons.

Guidelines for demolition with respect to the reuse of building materials

31

Nevertheless, one should be very careful in making such extrapolations, given the important differencesbetween the regions. 2.3 Bottle-necks A lot of bottle-necks for the recycling of construction and demolition waste can be indicated. they occur at the level of the production of the waste, the recycling activities and the use of recycled products. 2.3.1 The production of the wastes A distinction is to be made between road construction and construction of buildings, artworks,... Both sectors are producers of waste; both are potential clients. The rubble of roads is generally homogeneous and very well recyclable. Concrete as well as asphalt can be recycled, in situ as well as in centralised installations. The waste from construction and demolition of buildings is far more mixed up in comparison to the road. A bottle-neck is the separation of the different materials in order to get a reproducible and usable recycling products. More selective techniques of demolition are desired. Another bottle-neck could be the potential incertainity about the source of the wastes. The recycling company has to develop a good controlling system in order to avoid contaminated rubble. Taxes should be an efficient incentive for canalization of wastes to recycling plants. It can be a very effective instrument, but should also be handled with care, in order not to propagate illegal landfilling. 2.3.2 The recycling activity The profitability of recycling depend mainly on - the cost of the process - the (negative) value of the rubble. An important tool to raise in this negative value is the height of the taxes. However, as mentioned above they should be handled with care. - the difference in selling prices between virgin and the recycled materials (cfr. table 1)

Table 1: comparision of average selling prices

Gravel

porphyry

concrete

recycled mix

asphalt

320

310–390

220–240

180–200

230–280

Another bottle-neck is the legal incertainity about the responsibility. In other words: who’s responsible for the evacuation of contaminated batches.

Demolition and reuse of concrete and masonry

32

2.3.3 The use of the recycled products The first market for recycling products is road construction. If the use of these products is admitted; the quality can be certified and the price is interesting, a large market is created. It’s clear that the public market can and has to be extended. Nevertheless, this market isn’t huge enough to absorb all the recycled materials. New applications have to be developed, in the first place for the use of lower qualities (in the first place masonry granulates). 2.4 Potential incentives for the recycling of construction and demolition waste Several tools can be worked out in order to stimulate recycling: 1. The best way to stimulate recycling is to create or at least to enlarge the market. Recycled granulates should be used as much as technically sound in public works. This also has an effect on the private market, as private investors use the public standards. 2. The fear for lower quality puts a break on the use of recycled products. An official label can obviate these drawbacks if it constitutes a guarantee for a specific good quality. Such a label is to be well defined and given by an official body. 3. In order to obtain recyclable products and to canalise the wastes, new specifications for demolition works should be emitted and introduced in ‘demolition permits’. In the first place, this should be done for public works. 4. Creating a recycling industry is a task for the private sector, as it leads to an economical activity. With this new branch, the authorities can come to agreements in order to stimulate separation of the wastes and to enhance the recycling rates. 5. Higher taxes can be a tool for canalization of the wastes to recycling. They also have an effect on the profitability of recycling. 6. There is a need for new applications of recycled materials, especially for the lower qualities (masonry). Priority should be given to applications with high amounts of recycled granulates. 7. More and more precise information is to be reassembled about (among other things): - amounts and composition - comparison between different demolition techniques - .... 8. The authorities can prohibit landfilling. However, one should be very careful with such new prohibitions, because - there should be enough alternatives for the industry - illegal landfilling could be encouraged 9. Better control is necessary 10. Direct subsidisation of recycling doesn't seem to be effective. It will disturb the market and be very expensive.

Guidelines for demolition with respect to the reuse of building materials

33

These potential incentives can be classified following their cost-effectiveness.

Table 2: Potential incentives for stimulation of the reuse of construction and demolition waste: cost-effectiveness

For more details about initiatives in Belgium in the field of the use of secondary materials in public works, labelling and taxes, we refer to another lecture in this conference.(4) In the next paragraphs, attention will be paid to demolition and demolition guidelines. 3 Demolition 3.1 Requirements of the recycled granulates. Technical requirements Technical requirements of secondary granulates are treated more in detail in other lectures of this conference. They mainly consist of: - density: the quality of the end product is related to the density of the granulates. The higher the density, the better the strength of the concrete and the better the frostresistance.

Demolition and reuse of concrete and masonry

34

- absence of contaminations: some contaminations have a negative influence on the quality of the end products: organic material, iron, gypsum,… - granulometry: It is clear that the granulometry of secondary materials has to meet the same standards as virgin ones. Aggregates are used in different markets. A first important market consists of road construction. In Flanders, several different types of materials are defined: concrete rubble, mixed rubble masonry and asphalt. Each of these products can be used in well defined applications. More and more recyclers not only commercialise the granulates, but also produce concrete. These companies generally guarantee the features of the concrete. Obviously, analogous specifications for the granulates are applied. Environmental requirements As recycled materials are to be brought into the environment, they have to meet sound environmental standards. It is obvious that one has to avoid to bring heavy metals or other hazardous components into the environment. More details about this issue are presented in (4) 3.2 Requirements of the waste The requirements of the aggregates obviously are reflected in specifications for the waste. In the first place, the waste should be clean enough to produce the desired aggregates. However, in the recycling process, some cleaning steps are included; so a lot of contaminations (metals, plastics, wood,…) are removed. The presence of lower quantities (max some 10%) of these materials don’t cause major problems. For different fractions, one can determine the impurities which should be absolutely banned (red light), and those who are to be avoided (yellow light) (table 3)

Table 3: Requirements of the granulates

Fraction

To avoid

To ban

Concrete, porphyry,…

every other material

fibro cement,roofings packagings, insulation

Mixed rubble,… (incl. ceramics,…)

gypsum,wood plastics, wires,…

fibro cement,roofings packagings, insulation

Asphalt,…

gypsum, wood plastics, wires,…

fibro cement, packagings, insulation

Special attention is to be paid to materials, suspected from an environmental point of view. Pollution can originate from different sources, eg. hydrocarbons in gas stations, heavy metals in non ferro factories. Also carelessness can cause important contaminants (paintings, packagings, lamps,…)

Guidelines for demolition with respect to the reuse of building materials

35

At last, if the material is to be recycled, it has to be presented in a condition, that the recycling process can be applied in optimal conditions: not oversized, clean,… All these elements can be steered by the acceptation policy of recyclers. Different prices are applied for different fractions, and the freights, containing too much pollution or suspect materials are refused. Indicative prices are given in table 4.

Table 4: Prices for delivery of waste in recyling plants, average prices in Flanders

Fraction concrete, (clean, non reinforced2100kg/m3