新型粘土气凝胶对水泥砂浆性能的影响

Effect of New Clay Aerogel on Properties of Cement Mortar

气凝胶(Aerogel)由于其多孔的内部结构而具有出色的绝热性能。新开发的纳米蒙脱土类粘土气凝胶,由于具有良好的化学可塑性,在为水泥材料的功能化应用方面存在巨大潜能。本文研究了不同体积掺量的粘土气凝胶对水泥砂浆(水灰比分别为0.5和0.6)性能和机理的影响,包括力学性能、导热性能、吸水性能、水化程度,以及气凝胶微观结构的演变。结果表明,气凝胶作为细骨料掺入到水泥材料中,随着气凝胶体积掺量的增加,砂浆的力学性能,导热系数以及抗渗性均下降,其中导热系数最低可至0.093 W/(m·K)。当气凝胶体积掺量为80%时,其抗压强度为21 MPa。由于气凝胶结构疏松多孔,在凝胶老化收缩阶段可释放水分,提高砂浆养护后期的水化程度。根据扫描电镜照片观察到粘土气凝胶特有的微观层状结构,可以有效阻挡热量的传输,极大提高水泥材料的绝热性能。

Aerogel has excellent thermal insulation properties due to its porous internal structure.The newly developed nanomontmorillonite clay aerogel provides great potential for the functionalization of cement materials due to its good chemical plasticity.The effects of different volume content of clay aerogel on the performances of cement mortar(water-cement ratio is 0.5 and 0.6,respectively)were studied.The results show that as the aerogel content increases,the mechanical properties and thermal conductivity of the mortar decrease,and the thermal conductivity can be as low as 0.093 W/(m·K).When the volume of the aerogel is 80%,the compressive strength is 21 MPa.Due to the loose and porous structure of aerogel,water can be released in the aging and shrinkage stage of aerogel to improve the hydration degree in the later stage of mortar curing.According to the scanning electron microscope(SEM),the special microstructure of clay aerogel can effectively block the heat transfer and greatly improve the thermal insulation performance of cement.