Experimental Study On The Ultrasonic-rebound Combined Method For The Strength Of Rubber Concrete

This paper explored the applicability of nondestructive method for testing the rubber concrete strength ultrasonic method, which included the rebound method, the ultrasonic method and the ultrasonic-rebound combined method. It analyzed the precision of the three methods and also explored the applicability of different types of rebound hammer. It explored the testing accuracy with changing the rubber mixing amount, particle size, age and intensity.The main conclusions of this paper:(1) The ultrasonic method and the rebound method were used to characterize the strength of the rubber concrete with a single index, which had some limitations. They will produce some error with the influence of external factors. The sound speed value was affected by the age and moisture content. The spring back value was affected by the age of the instrument and the stability of the instrument.(2) Ultrasonic rebound combined method can solve a single test method to a certain extent, single test method to characterize the strength of rubber concrete defects. For detection of particle size for 60 mesh and 1~3 mm rubber concrete, it is suitable for selecting light hammer which the impact energy is 0.735 J. For detection of particle size of 3 ~ 6 mm rubber concrete, it is suitable for medium-sized rebound hammer which the impact energy is 2.207 J.(3) Nondestructive testing of rubber concrete strength will be limited by the source of the rubber material: If the source of the rubber used in the actual project was the rubber pad, it had great error that the strength of the rubber concrete was predicted by the curve in this paper. If the source of the rubber used in the actual project was the tyre, it had small error that the strength of the rubber concrete was predicted by the curve in this paper.