稻壳灰纤维水泥改性盐渍土的力学性能研究与机理分析

Study on Mechanical Properties and Mechanism Analysis of Modified Salted Soil with Rice Husk Gray Fiber Cement

为研究稻壳灰与聚丙烯纤维对使用水泥进行盐渍土加固方法的改良效果,制备水泥掺量为10%、纤维掺量为0.3%、纤维长度为12 mm、稻壳灰掺量为20%的稻壳灰纤维水泥加固盐渍土。对稻壳灰纤维水泥加固盐渍土的无侧限抗压强度、劈裂抗拉强度、CBR等力学性能进行了系统的试验,同时基于XRD与化学式分析探究了稻壳灰在水泥加固盐渍土中的改良机理。结果表明掺入稻壳灰与聚丙烯纤维的水泥改性盐渍土的力学性能要优于水泥盐渍土,60 d的无侧限抗压强度提高了31.9%、劈裂抗拉强度提高了49.1%,CBR值提高了16.52,通过XRD和化学式分析认为稻壳灰的掺入抑制了导致水泥加固盐渍土强度下降的Friedel盐的生成,并降低使水泥加固盐渍土膨胀的钙矾石(AFT)和钙硅石(CaSiO_(3))的浓度,生成了具有组成水泥骨架的水化硅酸钙,从而提高水泥土的力学性能。

For the purpose of studying the effect of adding rice husk ash and polypropylene fiber traditional cement reinforced saline soil method,the saline soil was strengthened with 10%cement,0.3%fiber,12 mm fiber length,20%rice husk ash cement.Having conducted systematic tests on the unconfined compressive strength test,splitting tensile strength test and CBR test of rice husk ash fiber cement reinforced saline soil,At the same time,the improvement mechanism of rice husk ash in cement reinforced saline soil was investigated based on XRD.The results show that the mechanical properties of cement-modified saline soil mixed with rice husk ash and polypropylene fiber are better than that of cement saline soil,60 d the unconfined compressive strength increased by 31.9%and the splitting tensile strength by 49.1%,An increase of 16.52%in CBR value,through XRD and chemical analysis,it is concluded that the incorporation of rice husk ash inhibits the formation of Friedel salt which leads to the decrease of the strength of cement reinforced saline soil,to reduce the concentration of ettringite(AFT)and calcium silicate(CaSiO_(3))that expand the cement reinforced saline soil,then improve the mechanical properties of cement soil.