A study on the uniaxial compressive behaviour of graded fiber reinforced concrete using glass fiber/steel fiber

Abstract

Hybrid fiber reinforced concrete (HyFRC) effectively utilises the combined benefits of different fiber types present in it for enhancing its properties. The mechanical behaviour of HyFRC with varying lengths of fibers was not completely understood to date, and hence, this study focuses on the uniaxial compressive behaviour of HyFRC with two different fiber lengths. In the first phase of the study, fresh properties and the uniaxial compressive behaviour of M30 grade mono glass fiber reinforced concrete (MGFRC) reinforced with glass fibers of 6 mm and 12 mm length and M30 grade mono steel fiber reinforced concrete (MSFRC) using crimped steel fibers of 25 mm and 50 mm length were evaluated and reported. In the second phase of investigation, fresh properties and uniaxial compressive behaviour of graded fiber reinforced concrete (GrFRC), obtained by blending two different lengths of fibers (Glass Fiber/Steel Fiber) were evaluated and reported. From the results, the uniaxial compressive response of the concrete was improved by the addition of glass fiber or steel fiber to the concrete. Graded FRC exhibited better synergy compared to Mono FRC in uniaxial compression for both glass and steel fiber reinforced concrete. Among all the MGFRC and GrGFRC mixes, GrGI combination (75% short length glass fiber + 25% long length glass fiber) grading of glass fibers exhibited better performance, similarly, of all MSFRC and GrSFRC mixes, GrSIII combination (25% short length steel fiber + 75% long length steel fiber) grading of steel fibers exhibited better performance. The addition of graded glass fibers to the concrete enhances the pre peak behaviour of the stress–strain curve considerably, and the addition of graded steel fibers to the concrete improves the post peak behaviour of the stress–strain curve remarkably. From this study, we can conclude that adding graded fibers (glass fiber/steel fiber) has proved to be advantageous in enhancing the uniaxial compressive behaviour of concrete.