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 the current main filling materials of MSW, such as high consumption of materials, high labour intensity and poor sealing effects. The material composition and structure were examined in this work and it was found that the performance of the SEFM-MSW was optimised with the addition of an expansion agent at a dosage of 0.4–1.0%, an admixture (dosage of 1.0–1.5%), fibre (dosage of 0.1%) and a water/cement ratio of 0.45–0.50. The relationship between the 28-day compressive strength and porosity of the SEFM-MSW could be expressed by an exponential function or a power function. The SEFM-MSW compressive strength decreased with an increase in porosity, which is consistent with the Ryshkewitch and Balshin models. The results also showed that when the expansion ratio of the SEFM-MSW was higher, the average pore size was larger, the pore size distribution was wider and the compressive strength was lower. The results of this study have realistic impacts for practical engineering applications.