Experimental Study on the Shear Behavior of Recycled Concrete with Artificial Sand

This study examines the shear behaviors of concrete structure with recycled concrete and artificial sand (AS). Thirty-six beams were prepared with two strength grades (C35, C45) and different artificial sand replacement rates (0%, 30%, 50%, 70%, and 100%). They were submitted to four-point static stress test in order to distinguish the shear behaviors of ASCRC (AS-containing recycled concrete) and of natural concrete that is fabricated using original coarse aggregate and natural sand. Experimental results found the shear strengths values of the ASCRC were lower than the nature ones, with decreasing extents less than 20%. When AS-containing level ranged from 30% to 70%, the cube compressive and shear strengths were more lower than other replacement ratios. Shear force-shear strain curve of the ASCRC was found similar to that of the nature concrete. The peak strain of the ASCRC rose with the increase of the shear strength, but the slope of the curves was lower.

Nonuniform Temperature Distribution in Adiabatic Shear Band Using Measured Shear Stress-Shear Strain Curve in Torsion of Thin-Walled Tube Aluminium Alloy Specimen and Gradient-Dependent Plasticity

Gradient-dependent plasticity where a characteristic length is involved to consider the microstructural effect (interactions and interplaying among microstructures due to the heterogeneous texture) and the measured nonlinear shear stress-shear strain curves for different loading strain rates are used to calculate the distribution of local temperature rise in adiabatic shear band (ASB) for aluminum-lithium alloy specimen of thin-walled tube in dynamic torsion test. ASB is assumed to initiate just at peak shear stress in the specimen. The temperature rise in ASB is decomposed into the uniform temperature rise in strain-hardening stage and the nonuniform temperature rise in strain-softening stage. The former depends on the measured nonlinear shear stress-shear strain curve prior to the peak, the density, the work to heat conversion factor and the heat capacity. The latter is related to the softening branch of the measured nonlinear shear stress-shear strain curve, the internal length parameter and the physical parameters. For binary Al-Li alloy, the predicted maximum temperatures in ASB are 413K at strain rate of 2000s-1 and 433K at strain rate of 2600s-1. These peak temperatures are lower than the recrystallization and phase transformation temperatures. Higher loading strain rate results in higher pre-peak and post-peak temperature rises, steeper profile of local temperature and higher peak local temperature in ASB. These predictions qualitatively agree with the previously analytical solution for ductile metal exhibiting linear strain-softening behavior beyond the peak shear stress based on gradient-dependent plasticity.