Study on methods of testing tensile strength of concrete

Abstract

Concrete is a brittle material in nature, having a low tensile strength; hence, indirect methods for testing the tensile strength of concrete are commonly used. This research attempts to investigate the applicability of a Modified Direct Tension Test (MDTT) method for determining the tensile strength of concrete using direct axial force and compares its performance with the Brazilian Splitting Test and Cube Compression Test across different concrete ages and grades. The experimental procedure involved testing concrete grades C25 and C35 at 3, 7, 14, 28, and 56 days. Tensile strength values obtained from both methods are analyzed and compared, alongside cube compression test results, to establish correlations between tensile and compressive strengths. The results suggest that the tensile strength vs compressive strength gain patterns vary with time for both tensile strength testing methods. It was also found out that the novel method provides consistent results, and the specimen modification made to direct the tensile crack at the center is successful in more than 80% of the cases. Practical applications for the MDTT are identified as Precast concrete evaluation, bridge and tunnel structural performance, and FRC & UPHC strength and quality assessments. Modifications to be made to the testing apparatus are also discussed.