Abstract:
The dynamic compressive behavior of hooked-end steel (HES) and macro-polypropylene (MPP) hybrid fibers reinforced recycled aggregate concrete (HyF/RAC) was studied. Three series (A, B and C) of HyF/RAC specimens were designed, which include three different recycled coarse aggregates (RCA) replacement ratios and five combinations of hybrid fibers at the total volume fraction of 1.5vol%, and four different strain rates were conducted. The results show that with the increase of strain rate, the peak stress, elastic modulus and compressive toughness increase, while the peak strain decreases. Compared with control groups in three series under the same strain rate, the largest increases of peak stress for specimens with fibers are 23%, 16% and 16%, respectively. The largest increases of peak strain are 19%, 12% and 13%, respectively. The largest increases of elastics modulus are 15%, 14% and 35%, respectively. The largest increases of compressive toughness are 46%, 32% and 37%, respectively. In the strain rate range, the strain rate sensitivity of peak stress, elastic modulus and compressive toughness increase with the RCA, and the RCA replacement ratio does not affect the strain rate sensitivity of peak strain. The strain rate sensitivity of peak strain and elastics modulus decrease with the addition of fiber. The addition of fibers enhances the strain rate sensitivity of peak stress and compressive toughness for natural aggregate concrete (NAC). While the strain rate sensitivity of peak stress and compressive toughness decrease for recycled aggregate concrete (RAC). The dynamic constitutive damage model was proposed considering the reinforcing index of fibers, RCA replacement ratio and strain rates. And all the models agree well with the experimental curves.