Assessment of Hydration Process And Mechanical Properties of Cemented Paste Backfill By Rebound Method

Abstract Backfilling mining method is a green mining method which is being used widely, nevertheless, the uniaxial compressive strength (UCS) of the cement backfill paste (CPB) on site is difficult to measure, and it is impossible to know the internal cementation, for this reason, the rebound method is improved and introduced in this paper. Standard specimens of CPB were made and cured for different curing age under standard curing conditions. The hardness test of each part of the CPB is completed, the unconfined compression test is carried out, and the functional model of the hardness of each part of the CPB is established, which was a function of radius and age. Based on the nonuniformity of the filling material, the failure mode of CPB is analyzed and verified in the test. The results show that the exponential function model is more suitable for the relationship between the external hardness and the overall strength, and this conclusion is of great significance in construction site. In addition, the corresponding relationship between hardness and local strength was calculated and verified, the results show that the simple model can predict the variation of local strength with hardness better, and the quadratic function model is the best choice.