膨润土浆液及其自凝灰浆黏度微观机理研究

Study on Microscopic Mechanism of Viscosity of Bentonite Grout and Its Self⁃Coagulating Mortar

不同厂家生产的钠基膨润土在相同配比要求下制备的自凝灰浆黏度差别很大,其本质是材料微观组分、结构不一致。基于SEM、XRD、EDS与NMR等微观试验,对两个厂家生产的同类钠基膨润土(简称湘源土和玉龙土)及其所制自凝灰浆进行试验分析,并据此对其黏度微观机理进行研究。结果如下:湘源土和玉龙土浆液黏度具有触变性,“卡片宫”的建立与Q~4结构的生成会促使其黏度上升,剪切作用会破坏微观结构使其黏度降低;湘源土蒙脱石含量高于玉龙土的,所以其浆液黏度整体高于玉龙土浆液。搅拌与低剪切作用促进蒙脱石颗粒小片层分散,小片层分散越多,停止剪切后膨润土浆液黏度越高。对于膨润土所制自凝灰浆,其黏度的变化主要依赖于内部电荷吸附与水化反应的程度,水化反应生成的C-S-H凝胶会促进浆液黏度提高。自凝灰浆在凝结过程中生成的碳硫硅酸钙不利于C-S-H凝胶生成,湘源土自凝灰浆碳硫硅酸钙含量高于玉龙土自凝灰浆的,所以其整体黏度低于玉龙土自凝灰浆的。

The viscosity of the same natrium-based bentonite produced by different manufacturers varies greatly when the self-setting mortar is prepared with the same ratio.The essence of the viscosity is caused by the discordant microstructure of the material.Based on SEM,XRD,EDS and NMR microscopic tests,the same bentonite produced by two different manufacturers and its self-coagulated mortar were analyzed,and the viscosity microscopic mechanism was studied.The main conclusions are as follows:a)For the two bentonite grout,the viscosity is thixotropic.The establishment of“card palace”and the formation of Q4 structure will increase the viscosity,while shear will destroy the mi-crostructure and reduce the viscosity.The content of bentonite montmorillonite from Xiangyuan is higher than that from Yulong soil,so its slurry viscosity is higher than that from Yulong soil as a whole.b)Agitation and low shear promote the dispersion of montmorillonite particles in small lamella.The more the dispersion of small lamella,the higher the viscosity of bentonite slurry after stopping shearing.c)For benton-ite self-coagulant slurry,its viscosity changes mainly depend on the degree of internal charge adsorption and hydration reaction,and the C-S-H gel generated by hydration reaction can promote the increase of slurry viscosity.d)The calcium carbonsulphosilicate generated in the process of condensation is not conducive to the formation of C-S-H gel.The content of calcium carbonsulphosilicate in Xiangyuan soil mortar is higher than that in Yulong soil mortar,so its overall viscosity is lower than that in Yulong soil mortar.