Strength effect and mechanism analysis of MICP-solidified coal ash

The coal ash has the characteristics of fine particles, small specific gravity and large pore ratio. In order to achieve effective utilization of the coal ash and dust pollution control, the microbial induced carbonate precipitation (MICP) method is used, considering natural evaporation and wet cylinder maintenance conditions, to study the mechanism of microbial response, strengthening characteristics and influencing factors. The results show that: (1) The calcite is the calcium carbonate produced by microorganisms in the coal ash, and the content increases from 7% to 15.3%. (2) Under the MICP wet cylinder curing conditions, the maximum unconfined compressive strength increases by 6.55 times, reaching 97.63 kPa. (3) The solidification strength first increases and then decreases with the increase of the nutrient concentration, and the optimal nutrient concentrations under moisturizing cylinder and natural evaporation conditions are 0.5 and 1.0 mol/L, respectively. (4) The microbial-derived calcium carbonate can reduce the water loss in ash samples and has a significant water retention effect, indicating good prospects for dust suppression applications.