Experimental study of a self-expanding filling material for mine-sealing walls

A self-expanding filling material for mine-sealing walls (SEFM–MSW) was developed to solve the problems of large solid material amounts, high labour intensities and poor sealing effects. This study examines material composition and structure. The results are as follows. First, the SEFM–MSW could be optimised with an expansion agent at 0.4∼1.0%, an admixture at 1.0∼1.5%, a fibre at 0.1% and a w/c (water/cement) ratio of 0.45∼0.5. Second, the fitting results were highly consistent of the relationship between the 28d-compressive strength and the porosity of the SEFM–MSW with the Ryshkewitch and Balshin models. Third, when the SEFM–MSW expansion ratio was higher, the average pore size was larger, the pore size distribution was wider and the compressive strength was lower. These results have realistic impacts for practical engineering applications.