Concrete Strength in Structures

Abstract

THE SIGNIFICANCE OF CONCRETE COMPRESSIVE STRENGTH MEASUREMENT BY VARIOUS METHODS WAS INVESTIGATED. PAIRS OF SLABS FROM THREE CONCRETES WERE SUBJECTED TO GOOD AND POOR CURING. CORES AND PUSH-OUT CYLINDERS WERE REMOVED AT SIX STAGES UP TO 1 YEAR AND TESTED FOR STRENGTH. CORRESPONDING TESTS OF MOLDED CYLINDERS BROUGHT THE TOTAL SPECIMENS TO 216 CORES, 216 PUSH-OUT CYLINDERS, AND 270 MOLDED CYLINDERS. THE DATA INDICATE THAT TWO CONCEPTS OF STRENGTH SHOULD BE DISTINGUISHED: (1) STRENGTH AS A MEASURE OF LOAD-CARRYING CAPACITY IN STRUCTURES, AND (2) STRENGTH AS A MEASURE OF CONCRETE QUALITY AND UNIFORMITY. THE RELATION OF THE LATTER (DETERMINED BY STANDARD CYLINDER TESTS) TO THE FORMER (DETERMINED ON CORES FROM THE STRUCTURE) IS EXTREMELY VARIABLE. /AUTHOR/