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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 20 Abstracts search results
Document:
SP76-18
Date:
October 1, 1982
Author(s):
Karim W. Nasser and H. M. Marzouk
Publication:
Symposium Papers
Volume:
76
Abstract:
The present tests were made to measure creep of mass concrete containing fly ash at six different temperatures of 70 to 450 F (21.4 to 232 C). At each temperature three stress levels were applied for over 20 months and they were 750, 1200, and 1500 psi (5.17, 8.27, and 10.34 MPa). The results showed that, in general, creep strains increased with a rise in temperature, and the maximum increase occurred at 450 F (232 C). It was also found that beyond 180 days, creep strains vary linearly with stress-strength ratios at temperatures of 70, 160, 350, and 450 F (21.4, 71, 177, and 232 C). However, at temperatures of 250 and 300 F (121 and 149 C), the strains were non-linear with stress-strength ratios at all ages. Based on the experimental results, a basic expression for creep of mass concrete containing fly ash at high temperature was suggested. Results of previous investigation on the effect of high temperature on the strength and elasticity of concrete con-taining fly ash were used to explain the creep behavior at various temperatures.
DOI:
10.14359/6799
SP76-19
Dobrosav Jevtic
Creep tests were conducted on a number of concrete specimens. Numerous prestressed concrete beams were tested for determining deflection, relaxation, and failure under long-term loading. Some of the tests are still in progress.
10.14359/6800
SP76-01
Max Zar
Creep, shrinkage, and temperature effects on concrete structures are discussed from a design perspective. Research into these problems and various solutions to these problems are looked at. Also emphasized is the importance of complex, sophisticated techniques of analysis for special structures, such as nuclear reactor containments.
10.14359/6782
SP76-02
Zdenek P. Bazant and Liisa Panula
A new model for the prediction of creep and shrinkage (which is presented in full detail elsewhere), along with a large scope verification by test data, is outlined in simple terms, explained and illustrated in this paper. In this model, the total creep strain is separated into the basic and drying creep components, but not into "reversible" and "irreversible" creep components. The effect of environmental relative humidity is modeled by vertical scaling of the drying creep term. The effect of specimen size is modeled by a horizontal shift of the drying creep term in the logarithmic time scale, and the basic creep term is unaffected by humidity and specimen size. The effects of humidity and size upon the drying creep are modeled completely analogously to those on shrinkage. The dependence of shrinkage as well as drying creep on the size of the cross section is introduced by means of shrinkage-square halftime, which is the same for both shrinkage and drying creep. Finally, the basic creep component of total creep strain is characterized by double power law.
10.14359/6783
SP76-03
Paul P. Kraai
Concrete drying shrinkage, as measured by ASTM C-157--Length Change of Hardened Cement Mortar and Concrete, represents a total value which is influenced by the cement type, aggregate source, and the test method. Based on available test data, percentage values can be assigned to each of the above contributions. One purpose of this paper is to show that ASTM C-157 is primarily a laboratory test and not a field test. A second purpose is to relate laboratory shrinkage to structure shrinkage. A third purpose is to relate the above shrinkagfe data to the volume change of field concrete which is also significantly influenced by ambient conditions.
10.14359/6784
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