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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 12 Abstracts search results
Document:
SP112-03
Date:
January 1, 1989
Author(s):
M. A. Taylor
Publication:
Symposium Papers
Volume:
112
Abstract:
Gamma-ray absorption techniques were used to determine the amounts of each component in a system of mixtures (such as concrete). The technique uses photons of several energies in contrast to previous applications where only one energy was employed. The use of multiple energies provides more information than the single-beam system, and thus more properties can be determined. Several possible models for cementitious materials are discussed and compared. The paper presents the experimental determination of the initial data set needed prior to prediction experiments. One predictive technique is evaluated by comparison with blind tests.
DOI:
10.14359/2362
SP112-04
M. Ohtsu
On the basis of the acoustic emission (AE) measuring technique, a diagnostic method for nondestructive evaluation of cracks in concrete is proposed. The diagnostics consist of a mechanical criterion of crack initiation, a quantitative waveform analysis of AE, the evaluation of deterioration by a test of core specimens, and the ultrasonic spectroscopic investigation of cracked members. Results of basic studies on these methods are summarized. Results of basic studies confirm the feasibility and the usefulness of the proposed method as diagnostics of cracks in concrete structures.
10.14359/2840
SP112-05
A. K. Maji and S.P. Shah
The fracture process of a composite material involves crushing or slippage of adjacent particles, microcracking, etc., resulting in changes in the load-versus-displacement behavior. A study of the fracture process is necessary to develop a rational material model. Laser holographic interferometry was applied to study the whole field deformation pattern. Speckle photography was used to measure quantitatively displacement discontinuities at bond cracks at various stages of loading. Acoustic emission (AE) techniques were applied to monitor microseismic activities resulting from the various fracture phenomena. The rate of microfracture was measured from the AE event rates. A source location algorithm was used to calculate the locations of the AE events. Specimens were made with different aggregate and void sizes to study their effect on crack patterns and load-displacement behaviors.
10.14359/2846
SP112-01
M. Sansalone and N. J. Carino
A nondestructive test method has been developed for locating defects in concrete. The technique is referred to as the impact-echo method and is based on monitoring surface displacements resulting from the interactions of transient stress waves with internal discontinuities. Paper describes the technique and presents results of laboratory studies designed to evaluate the capabilities of the method. These laboratory studies were carried out on 500 mm thick slabs that contained a variety of artificial flaws embedded at known locations. Frequency analysis of recorded time-domain waveforms is explained and shown to be a quick and simple signal processing technique. Finally, results are presented from a field study in which the impact-echo method was used to investigate a 150 mm thick slab believed to contain voids.
10.14359/3688
SP112-06
C. H. Yun, K. R. Choi, S. Y. Kim, and Y. C. Song
Presents an investigation to determine the within-test variability of various nondestructive test methods (NDT) and the correlation between NDT test results and the corresponding compressive strength of cores. The size effects of coarse aggregate on the variability and correlation were also evaluated. The NDT test methods evaluated in the test series include rebound hammer, pulse velocity, probe penetration, pullout, and CAPO (cut and pullout). Companion tests of field-cured standard cylinders and cores were also made at the ages when the NDT tests were made. Results show that the within-test variability of the in situ tests reported (except the pulse velocity test) is two to five times higher than that of the corresponding standard compression test and is affected significantly by the amount of coarse aggregate and its size. There is a good relationship between the results of in situ tests and the compressive strength. In general, the highest degree of correlation is for the pullout test followed by that for the CAPO (cut and pullout) test and rebound test, probe penetration test, and pulse velocity test.
10.14359/3706
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