Book Description

The concrete tests currently in widespread use were developed decades ago, and although there have been continual updates and refinements, there are inherent limitations which cannot be overlooked. Most important, current test methods are often rendered unrepresentative of the concrete in the field, especially at early ages or under different curing conditions. The study described herein was conducted to evaluate the applicability and effectiveness of several nondestructive test methods for assessing concrete strength in the field. The test methods used in this study included compressive cylinders, flexural beams, penetration resistance, rebound hammer, pullout, maturity, ultrasonic pulse velocity, and drilled cores. Test results from the different methods being evaluated were compared at concrete ages ranging from 1 to 28 days. Each test method was also evaluated for within-test variability among sets of companion specimens. Three different concrete mix designs were used, including cement plus fly ash contents ranging from 300 to 500 pounds per cubic yard, three maximum sizes of river gravels, and one maximum-size crushed limestone coarse aggregates.