International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP112-10

Date: 

January 1, 1989

Author(s):

T. J. Parson

Publication:

Symposium Papers

Volume:

112

Abstract:

Reports results of an investigation into the use of maturity for predicting early-age concrete strengths. Prediction models were developed from cylinder-test results obtained from twelve concrete mixtures cured under three constant curing conditions. A datum temperature of 25 F (-4 C) was used as it appeared to produce the best results. A prediction model based on estimated ultimate concrete strength was used and found to be independent of curing temperature. However, the estimated ultimate concrete strength value appeared to be dependent on curing temperature. The model was verified by using it to predict concrete strengths obtained from cylinders and slabs cured outdoors.

DOI:

10.14359/2372


Document: 

SP112

Date: 

January 1, 1989

Author(s):

Editor: H.S. Lew

Publication:

Symposium Papers

Volume:

112

Abstract:

SP112 Nondestructive Testing of Concrete has been especially prepared to present, examine, and promote the use of nondestructive testing techniques in concrete construction. Providing the latest information on the development and applications of nondestructive testing techniques, this collection of 11 papers will be of interest to anyone working in the field of concrete.

DOI:

10.14359/14145


Document: 

SP112-01

Date: 

January 1, 1989

Author(s):

M. Sansalone and N. J. Carino

Publication:

Symposium Papers

Volume:

112

Abstract:

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.

DOI:

10.14359/3688


Document: 

SP112-06

Date: 

January 1, 1989

Author(s):

C. H. Yun, K. R. Choi, S. Y. Kim, and Y. C. Song

Publication:

Symposium Papers

Volume:

112

Abstract:

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.

DOI:

10.14359/3706


Document: 

SP112-07

Date: 

January 1, 1989

Author(s):

G. V. Teodoru

Publication:

Symposium Papers

Volume:

112

Abstract:

Aim is to analyze the correlations between several nondestructive measured values (ultrasonic velocity and attenuation, rebound number) and the compressive strength of concrete. A computational program performs a step-by-step analysis. First, isolated linear correlations are established for each one of the three nondestructive tests. Then the results are compared with each other in the sense of a general multiple correlation of the values. Since the results obtained from the nondestructive tests are equally scattered, the program determines interactively, in a second step, the multiple coefficients of correlation and restarts the analysis several times by tentatively disregarding the presumably bad experimental results. Since the measured values also comprise a large spectrum of magnitude, limits of validity of the assumed correlations are investigated concomitantly with the process of analysis. A last step is performed to identify a tendency of deviation of the single and multiple correlations from the basic linear ones.

DOI:

10.14359/3715


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