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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 83 Abstracts search results
Document:
SP114-35
Date:
May 1, 1989
Author(s):
Chao-Lung Hwang and Dong-Sheng Wu
Publication:
Symposium Papers
Volume:
114
Abstract:
Rice husk ash (RHA) was obtained under different burning conditions from 400 to 1200 C. The changes in the properties of RHA were investigated by XRD, DAT, and microanalytical techniques. When RHA obtained at different burning conditions was added to cement paste or mortar, several properties such as hydration, setting time, porosity, and strength revealed changes.
DOI:
10.14359/2368
SP114-36
Terence C. Holland
The first silica fume admixture aimed at the ready-mixed market appeared in the United States in 1983. Since then, the use of silica fume has developed slowly. Currently, it is being used as a cement replacement material or as a performance-enhancing admixture. This paper reviews the practical aspects of working with silica fume in ready-mixed concrete, with an emphasis on the use of silica fume in the property enhancement role. The forms of silica fume currently being marketed in the United States are briefly described. Then, the current state of specifications for silica fume, admixtures containing silica fume, and concrete incorporating silica fume is examined. Next, aspects of concrete production are discussed. Finally, transporting, placing, finishing, and curing practices are reviewed.
10.14359/2376
SP114-37
Magne Maage
The term "efficiency factor" for condensed silica fume in concrete can be defined as the number of parts of cement that may be replaced by one part of silica fume without changing the property studied. This factor was first introduced for concrete compressive strength after 28 days curing in water at 20 C. In this situation, factors around 3 to 4 are reported. However, if the concrete is exposed to other temperatures, other curing conditions, or other curing periods, the factor may be as low as zero. This is very important information for the practical application of silica fume, especially when forms have to be stripped very early in winter concreting. The durability of concrete structures is more in focus than ever. When studying durability, the efficiency factors of silica fume in concrete can be calculated at the same time. Durability efficiency factors are also affected by the curing conditions. A comprehensive research program has enabled efficiency factors to be calculated for different conditions. This has covered strength and durability parameters such as permeability, carbonation, and chloride penetration. This work will be a helpful indication of how silica fume can be used in the most efficient way in concrete structures.
10.14359/2385
SP114-38
Motoharu Tamai
Cement paste with silica fume was used to improve strength and other characteristics of no-fines concrete. The results showed that by using cement paste with silica fume and superplasticizer, apparent viscosity and yield value of the paste in the fresh stage can be controlled. The compressive strength of no-fines concretes with silica fume is in the range of 20 to 47 MPa. Other characteristics such as flexural and splitting strengths, modulus of elasticity, and frost resistance of no-fines concrete are improved. The coefficient of water permeability varies depending on the amount of the continuous void and binder. A value of 2 to 50 mm/sec can be obtained.
10.14359/2395
SP114-67
Jean-Chuan Chern amd Ean-Chuan Chern and yin-Wen Chan
Presents results regarding the effects of various temperature and humidity environments on the compressive strength of concretes containing blast furnace slag cement (BFSC) and ordinary portland cement (OPC). Three types of blended cements containing 4.5, 35, and 68 percent slag weight replacements of portland cement were used. The specimens were stored in locations with controlled environments, such as 35 C (95 percent relative humidity), standard ambient temperature 23 C (lime water, sealed with polypropylene bag, 100 percent relative humidity fog room, and 50 percent relative humidity drying room), and 10 C. Test results indicate that the temperature effect on the initial rate of strength development of BFSC concrete is more sensitive than that of OPC concrete; high temperature accelerates the strength gain and low temperature suppresses the initial strength increase of BFSC concrete. Higher ultimate strength was achieved for the 4.5 and 35 percent BFSC well-cured concretes as compared to OPC concrete. However, the inadequate supply of reactive materials resulted in lower compressive strength for the 68 percent BFSC concrete. Under dry conditions, concrete with high slag content stopped its strength development as excess loss of moisture hindered the hydration process of cement. Strength degradation was also found for high slag content BFSC concrete.
10.14359/1800
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