Investigating the effectiveness of the stress-strain diagram on the rheological properties of fiber self-compacting concrete

Self-compacting concrete (SCC) containing fibers is a continuous compound, in which the fibers are dispersed throughout the concrete matrix and reduce shrinkage and microcracks. Furthermore, SCC properties such as filling capability and high efficiency produce a homogeneous mixture that could remove many problems of the conventional concrete. In this study, 10 mix designs were examined and tested, one of which was considered for the control sample and the other 9 designs included 0.25, 0.5, and 0.75 v/v% of steel, single-strand macrosynthetic (MEX 100), and carbon fiber reinforced polymer (CFRP) fibers. The rheological behavior of fresh SCC was investigated by the rheometer test as well as common tests used to determine the properties of fresh SCC, including slump flow, J-ring, L-box, U-box, and V-funnel tests. Then, the behavioral model of the hardened concrete was analyzed by tests determining mechanical properties such as compressive strength and modulus of elasticity. The results indicated adding fibers to fresh concrete reduced self-compacting and rheological properties of concrete; this effect became more visible with increasing the volume percentage of fibers, so that the greatest effect was observed in the design containing CFRP fibers. Results of mechanical properties of hardened concrete showed adding low volumes of fibers to SCCs improved some of these properties. However, using high volumes of fibers increased ductility and, thus, reduced compressive strength and modulus of elasticity in SCCs.