1、VOLUME 1 EDITOR v. M. MALHOTRA . REDACTEUR EN CHEF Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete Volume I Editor V. M. Malhotra international SP-199 DISCUSSION of individual papers in this symposium may be submitted in accordance with ge
2、neral requirements of the ACI Publication Policy to ACI headquarters at the address given below. Closing date for submission of discussion is October, 2001. All discussion approved by the Technical Activities Committee along with closing remarks by the authors will be published in the January/Februa
3、ry 2002 issue of either ACI Structural Journal or ACI Materials Journal depending on the subject emphasis of the individual paper. The Institute is not responsible for the statements or opinions expressed in its publications. Institute publications are not able to, nor intended to, supplant individu
4、al training, responsibility, or judgment of the user, or the supplier, of the information presented. The papers in this volume have been reviewed under Institute publication procedures by individuals expert in the subject areas of the papers. Copyright 2001 AMERICAN CONCRETE INSTITUTE P.O. Box 9094
5、Farmington Hills, Michigan 48333-9094 All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visual reproduction or
6、 for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. Printed in the United States of America Editorial production: Annette D. Pollington Library of Congress catalog card number: 200 l 090362 ISBN: 0-87031-026-7 PREFACE The
7、Canadian Centre for Mineral and Energy Technology (CANMET) of Natural Resources Canada, Ottawa, has played a significant role in Canada for over 30 years in research on fly ashes, ferrous and nonferrous slags, and silica fumes, in order to conserve both resources and energy, and to reduce C02 emissi
8、ons. In July-August 1983, CANMET, in association with the American Concrete Insti tute and the U.S. Corps of Engineers, sponsored a five-day international confer ence at Montebello, Quebec, Canada, on the Use of Fly Ash, Silica Fume, Slag and Other Mineral By-Products in Concrete. The main purpose o
9、f the conference was to bring together representatives from the industries, universities, and gov ernment agencies to present the latest information on these materials, and to explore new areas of needed research. The two-volume proceedings of the con ference containing 62 papers from 15 countries w
10、ere published as ACI Special Publication SP-79. In 1986, CANMET, in association with the American Concrete Institute, the Canadian Society for Civil Engineering, and a number of organizations in Spain, sponsored the Second International Conference on the subject of Fly Ash, Silica Fume, Slag, and Na
11、tural Pozzolans in Concrete. The conference was held April 21-25, 1986, in Madrid, Spain. The two-volume proceedings of the conference containing 72 refereed papers from more than 20 countries were published as ACI Special Publication SP-91. In 1989, CANMET, in association with the American Concrete
12、 Institute, Norwe gian Institute of Technology, and several other organizations in Canada and Nor way, sponsored the Third International Conference on the above subject. The conference was held June 18-23, 1989, in Trondheim, Norway. The two-volume proceedings of the conference containing 83 referee
13、d papers from more than 25 countries were published as ACI Special Publication SP-114. In 1992, CANMET, in association with the American Concrete Institute, Electric Power Research Institute, U.S.A., and several other organizations in Canada and Turkey, sponsored the Fourth International Conference
14、on the subject. The con ference was held May 3-8, 1992, in Istanbul, Turkey. More than 130 papers from 32 countries were received and reviewed in accordance with the policies of the American Concrete Institute; 89 refereed papers were accepted for publication as ACI Special Publication SP-132. Ill I
15、n 1995, CANMET, in association with the American Concrete Institute, Electric Power Research Institute, U.S.A., Canadian Electrical Association, Montreal, and several other organizations in Canada and the United States, sponsored the Fifth International Conference on the subject. The conference was
16、held June 4-9, 1995, in Milwaukee, U.S.A. The two-volume proceedings of the conference con taining 62 refereed papers from 23 countries were published as ACI Special Pub lication SP-153. In 1998, CANMET, in association with the American Concrete Institute, Electric Power Research Institute, U.S.A.,
17、and several other organizations in Canada and Thailand, sponsored the Sixth CANMET/ACI International Conference on the subject. The conference was held May 31-June 5, 1998, in Bangkok, Thailand. The two-volume proceedings of the conference containing 59 refereed papers from 26 countries were publish
18、ed as ACI Special Publication SP-178. In 2001, CANMET, in association with the American Concrete Institute, Electric Power Research Institute, U.S.A., and several other organizations in Canada and India, sponsored the Seventh CANMET I ACI International Conference on Fly Ash, Silica Fume, Slag, and N
19、atural Pozzolans in Concrete. The conference was held July 22-27, 2001, in Chennai (Madras), India. The two-volume proceedings of the conference, containing 54 refereed papers from more than 20 countries were published as ACI Special Publication SP-199. To all those whose submissions could not be in
20、cluded in the conference proceed ings, the Institute and the Conference Organizing Committee extended their appreciation for their interest and hard work. The refereed papers have been pub lished in two volumes. The first volume contains papers dealing with fly ash and natural pozzolans, and the sec
21、ond volume consists of papers dealing with silica fume, slag, and other materials. Some papers could have been published in either volume because the material covered more than one subject. In addition to the papers which have been published in these volumes, more than 40 other papers were presented
22、. Most of these papers were published as supple mentary papers, and the authors have been encouraged to publish them in techni cal journals of their choice. Thanks are extended to the members of the “Paper Review Panel“ which met at Torremolinos, Spain, June 11-17, 2000, to review the papers. Withou
23、t their dedi cated effort it would not have been possible to publish these volumes for distribu tion at the conference. The cooperation of the authors in accepting reviewers suggestions and revising their manuscripts accordingly is greatly appreciated. IV The help and assistance of Mr. H. S. Wilson,
24、 Consultant, Ottawa, Gordon D. Brearley and Maria Venturino of CANMET are gratefully acknowledged in the administrative work associated with the conference, and in processing of the manuscripts both for ACI proceedings and the supplementary volume. Thanks are also extended to A. Bilodeau (Chairman)
25、and Messrs. B. Fournier and R. Chevrier (Members) of the Slide Review Panel for their services to ensure that the slides meet the CANMET/ACI criterion. V. M. Malhotra, Editor Chairman, Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete July 2
26、001 v International Organizing Committee Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete Chennai (Madras), India July 22-27, 2001 Chairman Mohan Malhotra CANMET Ottawa, ON Theodore (Ted) Bremner University of New Brunswick Fredericton, NB W
27、ilbert (Wib) Langley W.S. Langley Concrete however, there were some exceptions. In general, the concentration of As leached from the fly ashes derived from the bituminous coals was much higher than that from the lignite or sub-bituminous coals. Regardless of the type and percentage of the fly ash us
28、ed, w/cm of the concrete, and curing condition, none of the trace metals in the leachates from the fly ash concrete samples exceeded the regulated concentration limits by the United States Environment Protection Agency and the Transportation of Dangerous Goods Act regulations of Canada. The concrete
29、 incorporating the fly ashes is, therefore, considered environmentally stable. Keywords: concrete; fly ash; leachability; trace metals 1 2 Zhang et al. Min-Hong Zhang is Associate Professor at the Department of Civil Engineering, the National University of Singapore. Prior to joining the university,
30、 she was a Research Scientist with CANMET, Natural Resources Canada. She is a member of ACI Committees 213, Lightweight Aggregate Concrete; 232, Fly Ash and Natural Pozzolans in Concrete; and 234, Silica Fume in Concrete. Marcia Bland1ette manages the Tailings and Waste Rock program in CANMET, Natur
31、al Resources Canada. She has over 10 years experience with environmental issues facing the mining industry in Canada, through her involvement with the Mine Environment Neutral Drainage (MEND) program, and activities within the Enviromnent Laboratory of CANMET. ACI Honorary Member V. Mohan Malhotra i
32、s Scientist Emeritus, International Centre for Sustainable Development of Cement and Concrete (ICON), CANMET, Ottawa, Canada. He is a fonner member of the ACI Board of Direction and has served on numerous ACI cmmnittees. He is a prolific author, editor, and researcher, and has received many awards a
33、nd honors from ACI and other institutions throughout the world. INTRODUCTION Portland cement concrete is and will remain a major construction material of choice. Unfortunately, the production of portland cement, the most important component of concrete, is very energy intensive. Furthennore, the man
34、ufocturing of portland cement is environmentally unfriendly because for each tonne of cement produced, approximately one tom1e of C02 is released into the atmosphere. Thus, replacing part of portland cement by mineral by-products such as fly ash or ground, granulated blast-furnace slag in concrete c
35、an contribute significantly to the reduction of C02 emissions, and savings in energy. There is a growing concern that the emissions of C02 and other greenhouse gases are affecting adversely the global climate. It is, therefore, imperative that policies and programs be developed to reduce the level o
36、f C02 emissions. The Canadian Government has announced that Canada, in accordance with the Kyoto Protocol, will reduce C02 e1nissions to about 6% below 1990 level by the year 2010. By replacing portland cement in concrete with fly ash, a by-product from the burning of coal in electric utilities, C02
37、 emissions can be reduced considerably that can help to meet the above objective. Typical replacement levels of fly ash in portland cement concrete are about 20% by mass of the total cementitious materials. With increasing use of fly ash in concrete, questions have been raised as to the potential co
38、ntamination of the surface and ground water by the trace elements in fly ash as a result of the leaching. Fly Ash, Silica Fume, and Slag 3 This paper presents infonnation on the leachability of trace elements from a number of fly ashes from Canadian and the U.S. sources, and from the concrete incorp
39、orating the fly ashes determined according to the United States Environment Protection Agency (EPA) regulatory method 1311 - Toxicity Characteristic Leaching Procedure (TCLP). The effects of fly ash source and content, w/cm, and curing conditions of the concrete on the leachability of trace metal el
40、ements were also evaluated. This study provides data that are not available in published literature. The effects of !taching conditions that simulate wetting and drying and the types of leachants on the leachahility of trace metal elements have been discussed elsewhere 1,2. LITERATURE REVIEW Publish
41、ed data have shown that the leachability of trace elements from a fly ash is dependent on the chenncal composition of the t1y ash, a function of the operating conditions ofthennal power plants 3, and the exposure conditions. The combustion temperatures of the boiler and the operating temperatures of
42、 the emission control devices are significant controlling parameters affecting the distribution of the trace elements in a coal ash. In most cases, for different coals burned in the same combustion unit under similar operating conditions, the distribution of most chemical species are similar 3; howe
43、ver, for different coals burned under different combustion conditions, no definite distribution pattern of trace elements can be detennined. Incomplete combustion can result in higher concentration ofleachable trace elements in a coal ash; and a coal with a lower heat content yields more leachable t
44、race elements, probably because of the lower combustion temperatures inside the furnace 3. De Groot et al. 4 investigated the leaching characteristics of selected trace elements such as arsenic (As), cadrnium (Cd), copper (Cu), antimony (Sb), selenium (Se), molybdenum (Mo), lead (Pb), tungsten (W),
45、vanadium(V), and zinc (Zn) from coal fly ashes as a function of the acidity of the leachant and the liquid/solid. The test consisted of three parts: a column-leaching test, a serial batch- leaching test, and a test for determining the maximum leachability. Fifty fly ashes from a wide variety of sour
46、ces were analysed, and only five fly ashes were tested using all the three tests. The authors found that with respect to leaching, differences in elemental composition of the fly ashes are far less important than the differences in the pH of the leachant. The pH level of a leachant is the controllin
47、g factor in the leachability of trace elements from a fly ash, and at a high pH ( 11) the solubility of trace elements is limited. All the ashes tested showed common leaching characteristics for several groups of elements. The trace elements present in the fonn of species, e.g. As, Sb, Se, Mo, W, an
48、d V, behave similarly, and showed a characteristic * Leachant is defined as a solution or liquid used for leaching. 4 Zhang et al. maximum leaching at neutral pH, and decrease in leaching towards lower and higher pH values. De Groot et al. 4 also found that the length of the batch-leaching test of 2
49、4-hour duration is sufficient for most elements to reach equilibrium, m1d can be a significant factor only for a few elements such as arsenic, Sb, and V at highly alkaline conditions and low liquid/solid for which the reaction kinetics me slow. The leaching characteristics of the fly ashes from the thennal power plants operated by Ontario Hydro, Toronto, Canada have been documented in a review report 5. Fly ashes derived from bituminous coals generally have higher content of the trace metal elements (As, Se, Cr, V, and Ti) than the fly ashes from lignite coals. The conc
