Multi-angle research on the performance of self-foaming filling materials and analysis of engineering applications

Utilizing self-foaming filling material to fill the hollow area is an effective way to settle the issues of low rate and poor effect of filling and roofing in the large stope. There are fewer studies related to the expansion rate, hydration exotherm and strength properties of self-foaming fillers in mines. Based on this, this paper investigates the expansion characteristics, hydration exothermic characteristics and compressive strength characteristics of the self-foaming filler under different cement-tailings ratios (1:4, 1:6, 1:8), reveals the hydration reaction mechanism of the material and its microscopic characteristics through XRD, TG and SEM tests, and evaluates the application effect and economy of the self-foaming filler in practical engineering with the background of Mashong Iron Ore Mine. The main findings are as follows: (1) The volumetric expansion of self-foaming filling material can be divided into the initial stage Ⅰ (0–1.5 h), the rapid reaction stage Ⅱ (1.5–8 h) and the stabilization stage, and as the cement-tailings ratio grows, the expansion rate of the filling body increases, and the expansion rate of the filling material with 1:4 ratio is as high as 20.4 %. (2) The hydration process of a self-foaming filled body does not contain induction and acceleration stages; under the same conditions, the self-foaming filled body has more exothermic heat of hydration than that of a self-foaming filled body by about 50 J/g, and the bigger the cement-tailings ratio, the bigger the hydration exothermic rate and exothermic quantity. (3) The compressive strength of self-foaming filler is inferior to the strength of conventional filler, the higher the cement-tailings ratio, the greater the degree of hydration, the more hydration products are produced, and the greater the compressive strength. (4) The bigger the ratio of gray sand, the greater the proportion of macropores and the actual engineering of self-foaming filling materials to catch the top rate of up to 98 %, directly saving the total cost of 11.6 %. The above research results can offer theoretical support and scientific guidance for the utilization of spontaneous foam materials to fill the goaf and control the roof rate, temperature, and strength of the stope. •Self-foam materials significantly increase the expansion rate of the filled body.•The hydration process of the self-foam material did not include the induction and acceleration stages.•The larger the cement-tailings ratio, the more hydra