Multiplication Factor of Actual Compressive Strength Relative to the Predicted Compressive Strength Obtained from Hammer Test Results

Abstract

Concrete is a composite material consisting of coarse aggregates, fine aggregates, water, and cement, with or without additional admixtures. In the construction of concrete structures, various problems are still frequently encountered, particularly when the implemented work does not meet the design specifications of the planned concrete strength. Therefore, it is necessary to evaluate the quality of concrete to determine whether it complies with the intended design strength. The compressive strength of concrete can be determined through two methods: destructive testing using a Compression Testing Machine (CTM) and non-destructive testing using a rebound hammer test. This study aims to determine the multiplication factor obtained from hammer test results in order to estimate the actual compressive strength of concrete. Additionally, the study compares the compressive strength values obtained from hammer test measurements with those obtained from compression testing. The research employed an experimental method using 60 normal concrete cube specimens. The results indicate that there is a significant difference between the actual compressive strength obtained from compression testing and the predicted compressive strength derived from the hammer test. The actual compressive strength values are higher by 23.35% compared to the vertical hammer test direction and 37.68% compared to the horizontal hammer test direction. The multiplication factor relating the actual compressive strength to the hammer test prediction is 1.3 for the vertical test direction (90⁰) and 1.6 for the horizontal test direction (180⁰).