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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:
SP112-08
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
SP112-09
C. J. Turkstra, P. Zoltanetzky, Jr., H. P. Lim, and C. Gordon
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.
10.14359/3736
SP112-11
R. L. Dilly and W. L. Vogt
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.
10.14359/3742
SP112-03
M. A. Taylor
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.
10.14359/2362
SP112-10
T. J. Parson
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.
10.14359/2372
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