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International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP92-08

Date: 

June 1, 1986

Author(s):

K. D. Hertz

Publication:

Symposium Papers

Volume:

92

Abstract:

The paper describes a new technique developed by the author for heating concrete rapidly by application of microwave power. Using an appropriate thermal insulation it is found to be possible to heat dry concrete specimens 10°C per minute and 20°C per minute avoiding the development of thermal stresses within the specimens. A series of 90 specimens has been heated 10°C per minute to various maximum temperature levels. The residual compressive strength was measured, and the results are compared to the similar results of the same concrete heated slowly. Applications for the technique are outlined, and a possible future development; is presented.

DOI:

10.14359/6516


Document: 

SP92-09

Date: 

June 1, 1986

Author(s):

T T. Lie, T. J. Rowe, and T. D. Lin

Publication:

Symposium Papers

Volume:

92

Abstract:

A study was carried out to assess the residual strength of reinforced concrete columns after exposure to a standard fire for various lengths of time, and cooling. The use of a mathematical model, an ultrasonic pulse test method and a load test method are investigated. Calculated temperatures and residual strengths of test columns were compared with those measured. Comparisons were also made between calculated and measured pulse velocities. The results indicated that using the calculation procedure and the method of measuring pulse velocity described in the study, the residual strength of concrete columns can be assessed with an accuracy sufficient for practical purposes.

DOI:

10.14359/6517


Document: 

SP92-02

Date: 

June 1, 1986

Author(s):

M. Diaz-Llanos, V. Sanchez Velasco, and I. Cerezo Preysler

Publication:

Symposium Papers

Volume:

92

Abstract:

In some cases, it is necessary to evaluate and document structures which were subjected to fires during construction. Due to the lack of official regulations on the subject, the analyses and documentation on these incidences, when reported to the regulatory authorities, implied unconventional activities, both for the utility and the A/E. The paper describes several fires affecting nuclear power plant concrete structures. They were all caused by inadvertent human actions. The presence of highly combustible auxiliary cons-truction materials contributed to their propagation. It is recommended that the cost (purchase and installation) of these auxiliary materials be evaluated against the use of alter nate (noncombustible)ones before making any decision, sufficiently in advance to avoid costly and time-consuming changes that may affect a usually tight schedule. As a result of visual inspection, followed by "in situ" and laboratory tests and engineering analyses of the affected elements, some elements had to be demolished and reconstructed while others were found to be acceptable.

DOI:

10.14359/6510


Document: 

SP92-01

Date: 

June 1, 1986

Author(s):

A. K. Tovey and R. N. Crook

Publication:

Symposium Papers

Volume:

92

Abstract:

This paper outlines the procedures adopted in obtaining information on fire-damaged concrete structures since 1975. Details are given on the information received from questionnaires and a summary of the building and construction types, damage and repairs are tabulated. The general conclusion is that concrete structures behave well under fire conditions with the majority of cases being repairable.

DOI:

10.14359/6509


Document: 

SP92-10

Date: 

June 1, 1986

Author(s):

P. J. E. Sullivan and G. A. Khoury

Publication:

Symposium Papers

Volume:

92

Abstract:

Generalised response curves for the transient thermal strain behaviour of concrete have been developed from a series of tests employing a wide range of materials and a lower than normal heating , rate. The latter allowed detailed assessment of underlying "material" behaviour to be made which was not complicated by "structural" effects that develop at a fast heating rate. The temperature, stress and moisture conditions within a cylindrical test specimen have been investigated and a study of the behaviour of individual constituents has confirmed that aggregate thermal stability is a critical factor. Thermal strains during virgin heating were separated into "Free" and "Load Induced" components possessing different and distinct properties allowing successful prediction of residual strains. A master with te m first h analysis the mast While t effect 0 clearly sensitiv thermal curve connecting Load Induced perature up to 450°C was found eating for different concretes of heated concrete structures er curve signified onset of c ransient creep did not occur duringf cracking caused bv thermal inc evident. Strain measurements, the indicators cycle. of damage taking Thermal Strain to exist during thus simplifying Departure from concrete damage. ing cooling, the ompatibility was harefore, proved place during the

DOI:

10.14359/6518


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