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International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP112-11

Date: 

January 1, 1989

Author(s):

R. L. Dilly and W. L. Vogt

Publication:

Symposium Papers

Volume:

112

Abstract:

Pullout testing and maturity have practical construction applications. Maturity is used to determine curing duration. The pullout test is used to determine in-place strength and to verify the adequacy of cure. Personal computers with spreadsheet software are tools that can benefit concrete construction. Templates developed using spreadsheet software can be used to acquire and analyze relationships between in-place strength and compressive strength, and maturity. Experimental investigations using pullout testing and maturity were undertaken and are reported using graphic features of spreadsheet software. The results of these experimental investigations show that curing environment can affect in-place strength relationships. Also, the results show that top to bottom strength differences can exist and should be considered when determining in-place strength. The results obtained using the compressible disk pullout assemblies indicate that this test method can be used to determine in-place strength without formwork removal, and the method should be further researched.

DOI:

10.14359/3742


Document: 

SP112-04

Date: 

January 1, 1989

Author(s):

M. Ohtsu

Publication:

Symposium Papers

Volume:

112

Abstract:

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.

DOI:

10.14359/2840


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: 

SP112-01

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: 

SP112-03

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


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