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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:
SP114-19
Date:
May 1, 1989
Author(s):
C. Lee
Publication:
Symposium Papers
Volume:
114
Abstract:
Effects of alkalies in Class C fly ash on Alkali-aggregate reaction were studied by using two cements, a type I high-alkali cement and a type II low-Alkali cement, and three Class C fly ashes. Mortar bar expansion was measured according to ASTM C 441. Reaction products of alkali-aggregate reaction were examined n by XRD, SEM, and EDAX. were to study: The purposes of this research (1) the significance of the standard mortar bar test in determining the degree to which high and low-alkali cement could be replaced by Class C fly ashes, and (2) effect of fly ash alkali contents on alkali reactivity. Expansion of mortar bars prepared using high-alkali cement increased at low replacement levels but decreased at high replacement levels for curing periods up to 12 weeks at 38 C; whereas expansion of mortars prepared using low-alkali cement increased at all Levels of fly ash replacements up to 40% by volume. A critical equivalent Na20/Si02 mole ratio was identified and found to characterize alkali reactivity. No crys-talline reaction products could be identified by XRD. Results of SEM and EDAX showed that the reaction product was an alkali-silicate gel, composed mainly of silica, sodium, potassium, and calcium, with their relative amounts varying within the gel.
DOI:
10.14359/10016
SP114-70
K. Byfors, G. Klingstedt, V. Lehtonen, H. Pyy, and L. Romben
Durability properties of concrete and mortar based on a special type of alkali-activated slag called F-cement have been studied. The microstructure was found to possess a high occurrence of microcracks that had an obvious influence on the flexural strength and rate of carbonation. The rate of chloride-ion diffusion was about 30 times lower than in the portland cement concrete. Salt scaling was found to depend solely on the water-to-binder ratio and is independent of the air content. Early freezing takes place when the strength exceeds 5 MPa, and F-mortar shows high chemical resistance against solutions of sodium, calcium, and magnesium chloride.
10.14359/1827
SP114-01
P. K. Mehta
Updates a 1983 critical review on pozzolanic and cementitious by-products for use in concrete. The by-products included in this report are fly ash, granulated blast-furnace slag, and condensed silica fume. Recently available worldwide statistics on production and utilization rates of these mineral admixtures are given. New information is presented on their physical and chemical characteristics, structure, and reactivity of the glassy phase, mechanisms by which concrete properties are enhanced, and engineering properties of concrete containing siliceous by-products. A special emphasis is given to durability aspects of concretes incorporating fly ash, blast-furnace slag, or condensed silica fume. Finally, the status of standard specifications and test methods is reviewed, and the contribution of siliceous by-products to make concrete an environment-friendly material of construction is emphasized.
10.14359/1835
SP114-71
D. J. Cook, I. Hinczak, M. Jedy, and H. T. Cao
Provides data from an investigation of the behavior of a range of concrete mixes made with blended cements stored in seawater. Three cements were used at binder contents of 280, 350, 420, and 550 kg/m3. Ground granulated blast furnace slag was used as a
10.14359/1838
SP114-02
V. Sivasundaram, G. G. Carette, and V. M. Malhotra
Presents results of investigations forming part of a long-term study of concrete incorporating low quantities of cement and high volumes of low-calcium (ASTM Class F) fly ash. Two types of low-calcium fly ashes from sources in Nova Scotia and Alberta were studied. For comparison purposes, a control concrete containing only ASTM Type I cement was also investigated. A large number of concrete test cylinders and prisms were subjected to determinations of strength, modulus of elasticity, drying shrinkage, freezing and thawing durability, carbonation, and permeability to chloride ions. The test results up to 1 year corroborate the results of previous investigations on concrete incorporating high volumes of low-calcium fly ash. At 7 and 28 days, the compressive strength and the modulus of elasticity were about 47 MPa and 37 GPa, respectively. Air-curing of test specimens did not seem to affect the compressive strength development significantly up to the testing period of 91 days. Resistance of all concretes to repeated cycles of freezing and thawing was found to be excellent with durability factors > 99, when tested after 14 days of the initial moist curing. The drying shrinkage strains of the fly ash concretes were comparable to or lower than that of the control concrete. Further, permeability tests carried out on one of the fly ash concretes indicated exceedingly low permeability to chloride ions at 1 year.
10.14359/1847
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