Experimental Study On The Modification Of Bentonite Based Cement Slurry

With the continuous development of Chinese economy,more and more cities begin to develop to the underground space and begin the construction of underground traffic.The water rich sandy pebble stratum is a common stratum in the city of our country.In the process of underground engineering construction,grouting treatment is often needed to ensure the safety of construction.According to the characteristics of water rich sandy cobble stratum,grouting material is required to achieve controllable gel time,good dynamic water resistance,stable strength,small permeability coefficient,and little environmental pollution.At present,the bentonite cement silicate sodium?BCS?double slurry system is a kind of slurry system which has been studied for the water rich sandy pebble stratum.Compared with the cement single slurry and the cement water glass double slurry,its injectability,impermeability and stability have been improved to a certain extent.However,the problems of water seepage and low early strength still appear in the actual project.Therefore,it is necessary to further improve the early strength and impermeability of the slurry.Nano materials have excellent physical and chemical properties,which can greatly improve the mechanical properties and durability of cement paste.In this paper,the basic parameters of BCS slurry after adding nano materials are explored and the micro theoretical analysis is carried out.Then,based on BCS slurry and nano SiO₂,a series of modification tests are carried out with additives such as ferroaluminate cement and early strength agent.The specific research contents are as follows:?1?Through basic tests,three basic performance parameters of viscosity,gel time and intensity of BCS slurry after adding nano materials were obtained.The change rules of slurry parameters were found under different dosages.The optimum range of application of nano materials was determined,and the better performance of nano SiO₂was selected for subsequent experiments.?2?The influence of nano materials on the performance parameters of BCS slurry was analyzed by the hydration kinetics model,which provided the basis for the later modification test.?3?The BCS slurry was modified by ferroaluminate cement,and the reason of low strength of the slurry was explored.?4?The BCS slurry was modified by bauxite,triethanolamine and its compound early strength agent.The effect of three early strength agents on the performance of BCS slurry was obtained.