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International Concrete Abstracts Portal

Showing 1-5 of 39 Abstracts search results

Document: 

SP121-36

Date: 

November 1, 1990

Author(s):

A. Takahata, T. Iwashimizu, and U. IshibashiI

Publication:

Symposium Papers

Volume:

121

Abstract:

Results of studies on the application of a high-strength concrete, with compressive strength of 42 to 60 MPa, to a high-rise reinforced concrete residence are presented. First, experiments were performed in accordance with the construction procedure, applying full-scale test structure modeling on part of the actual building. As a result, workable high-strength concrete was achieved by using a high-range water-reducing agent at the plant where concrete is being manufactured, and by adding a superplasticizer and placing the concrete carefully on site. In addition, for the quality control method of a ready-mixed concrete, water-cement ratio measurement before placement was useful. It is desirable to control the structure strength of high-strength concrete by not only using a test specimen cured in water on site, but also by taking out core specimens. Secondly, requirements for a construction method were set, by reference to the test results, and construction of the actual building was undertaken. Results of all the tests satisfied the requirements necessary to demonstrate the stable manufacturing control of ready-mixed concrete.

DOI:

10.14359/3448


Document: 

SP121-26

Date: 

November 1, 1990

Author(s):

P. Read, G. G. Carette, and V. M. Malhotra

Publication:

Symposium Papers

Volume:

121

Abstract:

Presents data at ages up to 1 year on the strength development characteristics of high-strength concrete ( > 80 MPa) incorporating blast furnace slag and/or silica fume or high volumes of ASTM Class F fly ash. Six concrete mixtures of various compositions were investigated in this study. Five of these mixtures had the same cementitious materials content of 485 kg/m3 of concrete, and the sixth mixture was typical of high-volume fly ash concrete incorporating a cement content of 150 kg/m3 of concrete and large volumes of fly ash. The concrete was obtained from a commercial ready-mixed concrete plant. For each mixture, three types of structural elements simulating a thick wall, a thin wall, and a thick column were fabricated for testing under field curing conditions. Cores, 100 x 200 mm in size, were drilled at ages up to 1 year for determining the in situ compressive strength of the various concrete elements. In addition, a number of 150 x 300 mm cylinders were cast from each mixture for long-term strength testing. The test results indicate that compressive strengths approaching 100 Mpa at 1 year can be achieved using a superplasticizer, with or without the use of supplementary cementing materials. The moist-cured test cylinders and the drilled cores from the various concrete elements indicate continued gain in strength of concrete at ages at least up to 365 days. The use of silica fume is generally required if high early-age strengths are to be achieved in structural elements. However, if high early-age strength is not a critical factor, then the high-volume fly ash concrete seems to be the most promising system.

DOI:

10.14359/2564


Document: 

SP121-38

Date: 

November 1, 1990

Author(s):

Kaare K. B. Dahl

Publication:

Symposium Papers

Volume:

121

Abstract:

Presents the results of an investigation undertaken at the Technical University of Denmark to determine the parameters that affect the ultimate load capacity of a concrete structure subjected to concentrated loads originating from reinforcement bars bent 90 deg. The following parameters have been found to have a decisive influence on the ultimate load capacity of the concrete bar: bar diameter, internal height of the specimen, side concrete cover, and concrete compressive strength. The results show that the relative load-carrying capacity of the concrete åc / fc decreases for increasing concrete compressive strength. However, the use of high-strength concrete (HSC) still results in an increase in the absolute load-carrying capacity of the concrete whencompared to normal strength concrete (NSC).

DOI:

10.14359/2870


Document: 

SP121-12

Date: 

November 1, 1990

Author(s):

L. Bjerkeli, A. Tomaszewicz, and J. J. Jensen

Publication:

Symposium Papers

Volume:

121

Abstract:

Paper summarizes results obtained as part of a recent research program on high-strength concrete (HSC). In this research, normal density concrete (mean cube strength of 65 to 115 MPa) and lightweight aggregate concrete (mean cube strength of 60 to 90 MPa)

DOI:

10.14359/2844


Document: 

SP121-31

Date: 

November 1, 1990

Author(s):

V. M. Malhotra

Publication:

Symposium Papers

Volume:

121

Abstract:

Reports results of a study undertaken to develop high-strength lightweight concrete having compressive strength of about 700 MPa and a density of less than 2000 kg/m3. The materials used consisted of an expanded shale lightweight aggregate of Canadian origin, ASTM Type III cement, low-calcium fly ash, and condensed silica fume. A series of 7 concrete mixtures involving 14 concrete batches were made. The cement or cementitious material content of the mixtures ranged from 300 to 600 kg/m3. All mixtures were air entrained and superplasticized. A large number of test cylinders and prisms were cast for the determination of mechanical properties and drying shrinkage of concrete. From the results of this investigation, it is concluded that concrete with a compressive strength of about 70 MPa at 365 days and density of less than 2000 kg/m3 can be made incorporating supplementary cementing materials. The highest compressive strength achieved was 69.3 MPa at 365 days for a mixture with a cementitious material content of 600 kg/m3 of concrete; the highest flexural strength obtained was 8.7 MPa at 28 days.

DOI:

10.14359/2567


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