Experimental Research on Dynamic Mechanical Properties of Rubber Concrete Subjected to Freeze-Thaw Cycles

In order to study the dynamic mechanical properties of rubber concrete under freeze-thaw cycles, the longitudinal wave velocity of rubber concrete specimens with 10% rubber volume was measured by non-metallic ultrasonic detector, the impact compression tests of rubber concrete specimens with different freeze-thaw cycles (0, 25, 50, 75, 100, 125) were carried out by using the 74 mm diameter variable cross-section split Hopkinson compression bar test device under different impact air pressures (0.3, 0.4, 0.5, 0.6 MPa), and the change laws of stress-strain curve, peak stress, ultimate strain dynamic intensity enhancement factor (DIF) and energy absorption effect were analyzed. The results showed that the strength of concrete decreased with the addition of rubber, but its toughness and energy absorption effect increased obviously. With the increase of freeze-thaw cycles, the longitudinal wave velocity of rubber concrete decreased and the damage degree increased. Freeze-thaw action would damage rubber concrete and reduce the longitudinal wave velocity of specimens. Under the same freeze-thaw cycles, with the increase of strain rate, the peak stress, limit strain, DIF and absorbed energy of specimen increased, and there was an obvious strain rate effect. Under the pressure of 0.6 MPa, the peak stresses of 25, 50, 75, 100 and 125 freeze-thaw cycles were reduced by 25.1%, 37.1%, 46%, 52.5% and 54.8%, respectively. With the increase of the number of freeze-thaw cycles, the peak stress of specimens decreased and the decreasing amplitude decreased gradually. After the number of cycles exceeded 100, the decreasing amplitude of stress of specimens was no longer obvious. The ultimate strain increased and the absorbed energy decreased. The freeze-thaw environment significantly reduced the strength and integrity of rubber concrete materials.