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International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

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: 

SP112-11

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: 

SP112-09

Date: 

January 1, 1989

Author(s):

C. J. Turkstra, P. Zoltanetzky, Jr., H. P. Lim, and C. Gordon

Publication:

Symposium Papers

Volume:

112

Abstract:

Presents a comparison of 28 day concrete strength as measured by field probe penetration tests and standard laboratory cylinders. Over a period of 11 months, 318 matched sets of tests were performed on 4000-psi concrete at four major projects. Primary field variables include the project location, operators, test guns, and the element type on which the field tests were made. Corrections to account for temperature variations are considered. Results include statistical analysis of the effects of test parameters and the correlation between field and laboratory results. Based on standard statistical tests, it is concluded that the variability of field probe results is similar to that of the corresponding laboratory cylinder tests. Results did not depend significantly on operators or the particular equipment used. However, results did depend significantly on the type of structural element tested and on the range setting of the firing gun. It is concluded that the calibration charts provided with the equipment should be reviewed.

DOI:

10.14359/3736

Document: 

SP112-08

Date: 

January 1, 1989

Author(s):

T. R. Harrell

Publication:

Symposium Papers

Volume:

112

Abstract:

A case history of methods used to evaluate the allowable form removal time for a large diameter tunnel concrete lining is presented. To meet schedule requirements, a concrete placement was to be made every alternate day. A triad of testing was done to evaluate the time at which the reusable, self-propelled, steel-skinned form could be stripped from an existing placement. This testing consisted of field-cured cylinders and nondestructive testing that included embedded thermocouples in the concrete placements and penetration-resistance testing. Reference curves and tables were developed for use in the form removal evaluation. Statistical methods were used on test data obtained from results of testing done with the actual concrete mix to be used in the placements. Control curves were then developed. Target values were selected to be used in determining when the concrete was of sufficient strength to allow for the form removal.

DOI:

10.14359/3726

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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