Title:
In Situ Strength Evaluation of Concrete
Case Histories and Laboratory Investigations
Author(s):
Rowland J. Kopf, Claude G. Cooper, and Freeman W. Williams
Publication:
Concrete International
Volume:
3
Issue:
3
Appears on pages(s):
66-71
Keywords:
compressive strength; concrete cores;
cubes; curing; cylinders; field tests; form removal; im-pact
tests; nondestructive tests; penetration tests;
post-tensioning; prestressing;
DOI:
Date:
3/1/1981
Abstract:
The critical need for reliable information on in situ strength of concrete, both for safety and economics, is discussed in detail. Included is the rate of strength gain under various curing conditions and available methods of determining variations in concrete strength in structural elements. Field data, illustrations, actual test reports, and photographs are presented as a proposed basis for determination of optimal methods and the need for proper judgement leading to statistical analysis of data. The interrelation of ACI 318 and 214, ASTM C 31, C 39, and C 42 as related to various building codes are reviewed with particular emphasis on certain ambiguities related to moisture condition at the time of test and reasonable adjustments allowable to arrive at meaningful conclusion. Included with field data of private consulting engineers, concrete product producers, and commercial testing laboratories are certain important federal agency reports on nondestructive in situ test methods.