Abstract:In order to study the effect of the replacement rate of recycled coarse aggregate on the compressive property of broken pebble concrete and the supersonic velocity of compressed concrete under different replacement rates, the standard cube test blocks with the replacement rates of 0%, 15%, 30% and 45% of recycled coarse aggregate were prepared for compressive property tests on days 3, 7, 14, 28 and 45 and compressive stress-ultrasonic velocity tests on days 28. The results show that with the increase of the substitution rate, the compressive strength of the cubes in each age increases first and then decreases. The trend is especially obvious at 3 days, and the trend becomes smaller after the age of 28 days. With the increase of compressive stress coefficient, the ultrasonic sound velocity at each substitution rate increases first and then decreases. When the compressive stress coefficient is 0.2, the maximum value is obtained. For the same compressive stress coefficient, with the increase of substitution rate, the variation trend of ultrasonic velocity is similar to that of compressive strength.