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