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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 34 Abstracts search results
Document:
SP171-27
Date:
August 1, 1997
Author(s):
0. A. Kayyali and M. N. Haque
Publication:
Symposium Papers
Volume:
171
Abstract:
Two types of lightweight concrete were investigated. The first was made with polystyrene beads and blast furnace slag aggregate. This concrete yielded a dry density value of about 1650 kg/m3 with a compressive strength of 30 MPa, moduli of rupture and elasticity values of 5.3 MPa and 20 GPa respectively. Drying shrinkage of this concrete was higher than that of normal weight concrete. The second type of concrete investigated was made from sintered fly ash aggregate as a total replacement of both coarse and fine aggregate. This concrete yielded a dry density of about 1790 kg/m3 and a compressive strength above 70 MPa, and values for the moduli of rupture and elasticity of 5.5 MPa and 21 GPa respectively. The stress-strain relationship of this concrete is a straight line till very near to failure thus underlining its brittle nature. the shrinkage values for this concrete are lower than normal weight concrete and this is attributed mainly to the excellent bond capability and to the high absorptive capacity of the aggregate. Expressions for predicting the moduli of rupture and elasticity provided by some codes of practice did not give accurate results specially when applied to the polystyrene beads type concrete. Addition of fly ash as a partial replacement of fines was beneficial in eliminating segregation and increasing workability and cohesion of the fresh concrete.
DOI:
10.14359/6116
SP171-28
M. Shoya, Y. Tsukinaga and S. Sugita
Three specific in-situ tests to assess the air tightness and water tightness of the surface layer of concrete were examined. Test methods for the tightness are the rapid air permeability, the water absorption applying Figg’s method and the rapid water permeability by author’s method. In the experiments, specific parameters obtained in three different in-situ tests corresponded well to air permeability coefficient and coefficient of water diffusion in the firms indoor tests, and those parameters satisfactorily reflect the change in the tightness of the surface layer caused by the water to cement ratio, age of test and cement type. Those parameters changed when measured at a relatively high temperature. In conclusion, three test methods are promising for providing air tightness or water tightness of the surface layer of concrete . from the view points of the use of simple testing devices and convenient procedures.
10.14359/6117
SP171-29
F. Omata, M. Kawakami, H. Tokushige and A. Moriyoshi
This paper describes changes of stress and strain during the setting of prismatic specimens incorporating polymer mortar. A new apparatus measures setting shrinkage stress and strains developed at both ends of polymer mortar specimens while at constant temperature. This apparatus is simple in structure, consisting of a noncontact type displacement device and a load measuring device. The relationships of setting shrinkage stresses and strains, and elastic modulus of three kinds of polymer mortar are reported. Furthermore, the mechanical properties of three kinds of polymer mortar were investigated. Finally, the deflection and strain that occur when polymer mortar is overlaid on ALC (Autoclaved light weight concrete) beams includes both analysis and experimental data on the two layered structure.
10.14359/6118
SP171-30
Jan Skalny, Vagn Johansen and F. M. Miller
It has been reported that the chemical/mineralogical composition of modern Portland-cement clinkers has changed in recent years to such a degree that cements made from them may lead to concrete durability problems even if such cement passed the applicable specifications. The effect of sulfur compounds in clinker on concrete deterioration due to delayed ettringite formation is cited as an example. In this paper, the relevant issues are briefly evaluated in light of available laboratory data and field experience.
10.14359/6119
SP171-31
J. Stark and N. Chelouah
Deicing salt scaling resistance of high-strength concrete with a water-cement ratio < 0.40 remains clearly under the CDF (Capillary Suction of Deicing Chemicals and Freeze-Thaw Test) acceptance criterion of 1,500 g/m* after 28 freezing and thawing cycles even if no air-entrainment is used. It was confirmed by our investigations that a high-strength concrete without air-entrainment and with a low water-cement ratio and consequently almost no capillary pores may have a very high freeze-deicing salt resistance. The effect of phase transformations in hydrated cement under freeze-deicing salt attack which is practically harmless in air-entrained concretes should, however, be taken into consideration when dealing with high-strength concretes without air-entrainment.
10.14359/6120
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