活性氧化镁−微生物固化黄土试验研究

以活性氧化镁和微生物共同作用固化的黄土试样为研究对象，通过含水率、无侧限抗压强度、X射线衍射（XRD）和扫描电镜（SEM）等试验，研究了活性氧化镁掺量、养护龄期和初始含水率对固化试样含水率、无侧限抗压强度、固化产物和微观结构等的影响。结果表明：固化试样含水率随氧化镁掺量增加和养护龄期增长而降低；无侧限抗压强度随活性氧化镁掺量（5%～20%）增加而增大，随龄期发展总体上不断增大，但当氧化镁掺量为10%和15%时，后期强度稍有降低；当氧化镁掺量为5%和10%时，无侧限抗压强度随初始含水率增加而减小，而当氧化镁掺量为15%和20%时，无侧限抗压强度随初始含水率增加先增大后减小。XRD和SEM结果显示，随着氧化镁掺量增加，水化后未进一步反应的氢氧化镁越多；反应生成的水合碳酸镁具有膨胀性和胶结性，对土颗粒间缝隙进行填充，并将土颗粒胶结在一起。

Experimental study on solidified loess by microbes and reactive magnesium oxide

The loess samples solidified by reactive magnesium oxide (MgO) and microbes are analyzed in this paper. Water content and unconfined compressive strength are measured, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) are conducted on different samples to investigate the curing product and microstructure change with varying amount of reactive MgO, curing time duration, initial water content. The results show that the water content of solidified sample decreases with the increasing content of reactive MgO and the growing curing period. The unconfined compression strength increases with the increasing content of reactive MgO, and also increases with the growing curing period in general, but decreases slightly in the later period with the content of reactive MgO being 10% or 15%. With the increase of initial water content, the unconfined compressive strength of solidified samples decreases when the reactive MgO content is 5% or 10%. But it will first increase and then decrease while the amount of reactive MgO is 15% or 20%. The results of XRD and SEM tests show that the higher the content of reactive MgO, the more magnesium hydroxide remains. The hydrated magnesium carbonate produced by the reaction is swellable and cementitious, which can fill the gaps between the soil particles and cement the soil particles together.