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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 62 Abstracts search results
Document:
SP179-29
Date:
June 1, 1998
Author(s):
V.K.R. Kodur and Mohamed Sultan
Publication:
Symposium Papers
Volume:
179
Abstract:
In recent years, high strength concrete (HSC) has become an attractive alternative to traditional normal strength concrete (NSC). With the increased use of HSC, concern has developed regarding the behaviour of such concrete in fire. Studies are in progress at National Research Council of Canada for developing design guidelines for the use of HSC under fire conditions. The behaviour of HSC columns is illustrated by comparing the fire resistance performance of HSC columns with that of NSC columns. Results from experimental studies that were carried out to determine the thermal properties of HSC, with and without steel fibre-reinforcement, at elevated temperatures are also presented. The effect of temperature on thermal conductivity, thermal expansion, specific heat and mass loss of HSC is discussed. Test data indicate that the type of aggregate has significant influence on the thermal properties of HSC, while the presence of steel fibre-reinforcement has very little influence on the thermal properties of HSC.
DOI:
10.14359/6056
SP179-30
A. Ueno, K. Kokubu and H. Ohga
This paper describes a basic study on the development of a new method to judge the saturated surface-dry condition of fine aggregates. The new method is based on the idea that the electric resistance of a sample depends on the moisture content of the sample. The relationship of the electric resistance with the moisture content of a sample is directly and radically changed by the existence of water on the surfaces of the particles. This becomes clearer when an electrolyte is added to the sample. The relationships between the electric resistance and the moisture content of a sample were investigated for various types of fine aggregates when an electrolyte was added. This relationship shows radical changes in the electric resistance near the saturated surface-dry condition. The chemical compositions of a sample do not influence the relationship of the electric resistance with the total moisture content of the sample. The applicability of the electric resistance test will be confirmed if the data of specimens with various physical properties will be investigated statistically.
10.14359/6057
SP179-31
N. Yuasa, Y. Kasai and I. Matsui
Measuring sensor made of ceramic have been studied for measuring the moisture content of concrete. As a result, the moisture content distribution inside concrete has been clarified. Furthermore, a moisture content measuring sensor equipped with small stainless steel electrodes, measuring 0.7 mm in diameter and 20 mm in length, were developed for the current study to locally measure the moisture content distribution inside concrete, thereby examining the temperature, applied voltage, influence of metal near the electrodes, and the coefficient of variation of specific electrical resistance during the test.
10.14359/6058
SP179-32
S. Nagataki, T. Kamada and A. Matsumoto
In this paper, a method to evaluate the crack size of concrete structures by infrared thermography was investigated. This method is based on the relation between the crack depth or width and thermal distribution in concrete. First, the influence of crack depth and width to thermal distribution was examined. Next, the influence of the distance between cracks and heater to thermal distribution was investigated. The effectiveness of this method was confirmed by the results of the experiment on flexural cracks in reinforced concrete beams. From these results, it was demonstrated that the thermal distribution measured at the surface of concrete by infrared thermography was effective in evaluating the crack size in concrete structures.
10.14359/6059
SP179-33
T. Katayama
Thin-section petrography, coupled with quantitative electron-probe microanalysis, is very useful in identifying reactive constituents and alkali-aggregate reaction in concretes, as well as in characterizing the nature of cement constituents, reaction products and gel products in old deteriorated concretes. EPMA analysis made it possible to detect chemical compositions of the unhydrated cement phases alite, belite, tricalcium aluminate, and the ferrite phase in the original cement used in old structures from Canada and Japan, made even 100 years ago. Coupled with detailed petrography in thin section, this technique also enabled us to estimate the thermal histories and composition of cement clinkers in hardened concretes, variations of CSH gels which reflect the degree of cement hydration, leaching and weathering of concretes, as well as the process of migration and alteration of ASR gels in concretes. The results thus obtained can be used for the assessment of cement properties and the durability of old concretes.
10.14359/6060
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