MICP固化粉煤灰的强度效应与机制分析

Strength effect and mechanism analysis of MICP-solidified coal ash

粉煤灰具有颗粒细、相对质量密度小、孔隙比大的特点,为了实现粉煤灰的有效利用和粉尘污染控制,应用微生物诱导碳酸盐沉淀(MICP)方法,考虑自然蒸发和湿缸养护两种条件,研究了微生物反应机理、强化特性及影响因素。结果表明:①微生物在粉煤灰中产生的碳酸钙为方解石,含量从7%最大增加到15.3%;②MICP湿缸固化条件下,无侧限抗压强度最大提高6.55倍,达97.63 kPa;③固化强度随营养物浓度的增加表现为先增大后降低,保湿缸和自然蒸发条件下的最佳营养浓度分别为0.5 mol/L和1.0 mol/L;④微生物固化粉煤灰可以减少内部水分损失,保水效果明显,还具有良好的抑尘应用前景。

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.