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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 78 Abstracts search results
Document:
SP91
Date:
February 1, 1986
Author(s):
Editor: V.M. Malhotra
Publication:
Symposium Papers
Volume:
91
Abstract:
SP91 This contains 78 symposium papers, bringing together the expertise of representatives from industry, government and universities. These volumes present the latest advances in the use of fly ash, silica fume, slag and natural pozzolans in concrete. New technologies are explored to provide ways in which these valuable mineral by-products can best be used to conserve both resources and energy. Case studies include: the effect of fly ash on physical properties of concrete; evaluation of kiln dust in concrete; effect of condensed silica fume on the strength development of concrete, and the influence of slag cement on the water sorptivity of concrete.
DOI:
10.14359/14048
SP91-35
G. L. Valenti, R. Cioffi, and R. Sersale
The fly ashes produced in Italy generally show good pozzolanic behaviour. Tests made on lime and cement mortars have shown that 4 of the 5 ashes give comparable or even superior performance to that of a natural pozzolan usually employed in the production of portland pozzolan cements. The chemical characteristics were: Si02 42.7-50.2%; Si02+A1203 66.5-77.2%; Si02+A1203+Fe203 75.8-83.5%; loss on ignition 3.9-12.9% and CaO 1.8-9.3%. The calcium oxide content is the parameter that greatly influences the technical behaviour. Glass content ranging from 63 to 75% does not have a dominant influence on mechanical strength. The particle size distribution, rather than the fraction <45pm determines the mechanical characteristics.
10.14359/10095
SP91-36
Traian Ispas and Ion Ionescu
Fly ash concretes with and without superplasticizers, hardened under normal conditions of temperature and by heat treatment. The influence of superplasticizers on the harde fly ash concretes was studied at ages (24-72 hours) days. ning process of and 28-730 Some technico-economic advantages resulting from the use of FA and superplasticizer admixtures in concrete are discussed in terms of design, production and standards development.
10.14359/10096
SP91-37
A. Bentur, M. Ish-Shalom, M. Ben-Bassat, and T. Grinberg
In recent years there has been a renewed interest in the utilization of oil shales as a source for energy production and this was accompanied by research and development aimed at finding ways to utilize the ash by-product as a building material. The present paper discusses the various types of oil shale ash and their possible applications, and reviews recent studies carried out in Israel to utilize the cementitious characteristics of oil shale ash. The composition and properties of the oil shale ash can vary widely, ranging from high SiO2 materials which are only pozzolanic in nature, to higher CaO oil shale ash which can be hydraulic and can serve as a cementitious matrix without any need for an activator. Therefore, each type of oil shale ash must be evaluated separately. The experience and knowhow gained in the application of one kind of oil shale ash may not be relevant to others. This is considerably different than with other residues, such as fly ash, which do not exhibit this extent of variable properties.
10.14359/10097
SP91-38
A. Verhasselt
The use of fly ash as a mineral admixture for lean concrete (road base concrete) has aroused a rather limited interest until now. However this comparative study shows that there are so-me advantages in using low calcium fly ash in lean concretes. The compactibility of lean concrete is improved : the maximum level of compaction (Modified Proctor test) is achieved at about 5 % fly ash addition, whereas it is equal at 0 % and 10 % addition . The CBR-indexes of the mixes are similar at Proctor maximum, but the higher the fly ash content, the more sensitive the index is to an increase in moisture content. At an early stage, fly ash is not very effective in strength development : it is essentially the portland cement content (2 to 5 %) that governs the rate of strength evolution. On the other hand, at longer periods (more than six months), fly ash contributes very largely to strength : a factor of 1.5 between the weakest mix and the reference lean concrete without fly ash. Accordingly a reduction of the cement content in practice can be taken into consideration. Water stability which is obtained rapidly, is not much affec-ted by the presence of the admixture. On the other hand, resistance to repeated freezing and thawing cycles is delayed because of the slower strength gain for mixes containing more fly ash and less cement. The results on the whole show that the optimum low-calcium fly ash content in lean concrete for road base lies around 5 % by mass with the possibility of reducing the cement content appreciably.
10.14359/10098
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