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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:
SP114-68
Date:
May 1, 1989
Author(s):
M. H. Decter, N. R. Short, C. L. Page, and D. D. Higgins
Publication:
Symposium Papers
Volume:
114
Abstract:
Penetration of chloride ions from the environment into reinforced concrete is important in relation to corrosion behavior of embedded steel. Blended cements containing ground granulated blast furnace slag (GGBFS) are expected to offer a greater degree of protection compared to that of OPC. The kinetics of chloride ion diffusion through hardened cement pastes made from SRPC, OPC, and OPC/GGBFS blends have been determined by a steady-state (thin disc) method. Concrete slabs containing similar cements and quartzite aggregate have been made and ponded regularly with 5 percent NaCl solution. Material taken from various depths within these slabs has been subjected to pore solution expression and analysis, and the concentration profiles of free and total chloride have been determined. Values of chloride diffusivity obtained by the steady-state method have been used to calculate the chloride concentration profiles expected when penetration is into a semi-infinite medium. Comparison between the two techniques shows the same general trends in relative performance of the various cements, but actual chloride concentrations, at a given depth, are greater in the concrete slabs. Results from total and free chloride measurements indicate that the chloride-binding capacity of slag cements exceeds that of OPC and SRPC.
DOI:
10.14359/1810
SP114-15
R. S. Barrow, K. M. Hadchiti, P. M. Carrasquillo, and R. L. Carrasquillo
A research program was conducted in which the temperature rise of mortars and the durability of concrete containing fly ash were studied. The study of the effect of fly ash on the temperature rise of mortars included the use of both ASTM C 618 Class C and Class F fly ashes. Control tests were conducted on mortars containing ASTM C 150 Type I, Type I-II, and Type III cements, and comparison tests were conducted on mortars containing 20, 27.5, and 35 percent fly ash by volume of cement. It was found that the use of Class F fly ash resulted in a reduction in the temperature of the mortar, whereas the partial replacement of cement with Class C fly ash did not lower the mortar temperature, regardless of the type of cement used. Resistance to scaling in the presence of deicing salts and abrasion resistance tests were conducted on concrete samples cast from 21 batches of concrete. Variables studied included fly ash type, fly ash content, and curing conditions. Both ASTM Class F and Class C fly ashes were used to replace 25 or 35 percent of the cement by volume, and curing conditions included combinations of 50, 75, and 100 F with 50 and 100 percent relative humidities.
10.14359/2022
SP114-35
Chao-Lung Hwang and Dong-Sheng Wu
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.
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
SP114-70
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
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