Biaxial Behavior of Steel Fiber–Reinforced Recycled-Aggregate Concrete Subjected to Dynamic Compression

Abstract

This paper presented an experimental study on the dynamic biaxial mechanical behavior of steel fiber-reinforced recycled-aggregate concrete (SFRRAC) samples. Five control variables, including lateral pressure (σ2), strain rates (ε˙), volume content of steel fibers (Vsf), volume content of polyvinyl-alcohol fibers (Vpf), and substitution ratio of recycled coarse aggregate (SRCA) were designed. Under different values of σ2, two distinct failure modes of samples were observed: columnar failure and oblique shear failure. However, the failure modes showed no substantial differences at various values of ε˙, Vsf, Vpf, and SRCA. The results indicated that the biaxial strength exhibited a general trend of initially increasing and then decreasing with increasing σ2. Specially, the biaxial strength exhibited a maximum increase of approximately 67% when σ2 reached 40 MPa. The lateral pressure was more significant than the strain rate in terms of material strengthening. The dynamic biaxial strength exhibited a linear correlation with the logarithm of the strain rate. The incorporation of steel fibers and polyvinyl-alcohol (PVA) fibers resulted in a slight 9.3% improvement in biaxial strength but significantly improved its deformation capacity. To achieve maximum strength, the optimal values of Vsf and Vpf were found to be 1.2% and 0.1%, respectively. With SRCA increasing from 0% to 100%, the biaxial strength decreased by approximately 11%. Moreover, this paper proposed two dynamic failure criteria, one in the principal and the other in the octahedral stress spaces. These criteria exhibited good agreement with the experimental data.