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International Concrete Abstracts Portal

Showing 1-5 of 83 Abstracts search results

Document: 

SP114-15

Date: 

May 1, 1989

Author(s):

R. S. Barrow, K. M. Hadchiti, P. M. Carrasquillo, and R. L. Carrasquillo

Publication:

Symposium Papers

Volume:

114

Abstract:

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.

DOI:

10.14359/2022


Document: 

SP114-27

Date: 

May 1, 1989

Author(s):

Mark D. Luther and Will Hansen

Publication:

Symposium Papers

Volume:

114

Abstract:

The specific creep and shrinkage of five high-strength concrete mixtures were monitored for 400 days at the University of Michigan, Ann Arbor. One 52.6 MPa (7630 psi) silica fume (SF) concrete was compared with a fly ash concrete of similar compressive strength, and SR concrete and fly ash concrete having compressive strengths of approximately 69 MPa (10,000 psi) were compared. A 106.6 MPa (15,450 psi) SF concrete was also studied. The creep of SF concretes was not significantly different from that of the fly ash concretes. Furthermore, the relationship between creep and compressive strength was consistent with that reported in the open literature for high-strength portland cement concretes. Several other concrete properties were studied, including slump retention, time of setting, compressive strength development for one year, split-tensile strength, modulus of rupture, and for the nominal 69 Mpa concretes only, rapid freezing and thawing durability and the hardened concrete air-void system.

DOI:

10.14359/2166


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


Document: 

SP114-28

Date: 

May 1, 1989

Author(s):

Lin IAoyu, Lu Anqi, and Xu Pengfei

Publication:

Symposium Papers

Volume:

114

Abstract:

Presents experimental results on the use of concrete incorporating condensed silica fume and fly ash to reduce cement content, to lower temperature rise due to hydration, and to enhance early strength, and gives a case history on the application of this type of concrete in the construction of turbine shells in China. Studies were done on the effect of adding different amounts of silica fume and fly ash on strength, the effect of addition of both silica fume and fly ash on the total heat of hydration, and properties of concrete, including setting time, slump loss, modulus of elasticity, ultimate elongation, impermeability, and resistance to abrasion. Experimental and field studies indicated that the concrete mixture containing condensed silica fume and fly ash helped save 38 percent cement, lower the heat of hydration by 40 percent, and showed a slight increase in strength and durability. In placing over 200 mý of concrete of this type in hot weather, no abnormal phenomena occurred during the operation. A 90-day compressive strength of 30 MPa and a 98 percent strength were obtained, meeting the design strength requirements. No crack has been found in the surface of the shells since they were completed half a year ago.

DOI:

10.14359/2104


Document: 

SP114-36

Date: 

May 1, 1989

Author(s):

Terence C. Holland

Publication:

Symposium Papers

Volume:

114

Abstract:

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.

DOI:

10.14359/2376


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