改性糯米灰浆固化黄土的微观机理试验研究

A test study of the microscopic mechanism of modified glutinous rice mortar solidified loess

黄土的水敏性是影响黄土地区土遗址保护与修复的重要因素,陕北革命遗址中以黄土窑洞为主的遗址由于黄土水敏性导致了窑洞墙面的脱落、粉化及渗水等病害,利用改性糯米灰浆固化黄土作为墙面修复材料,其改善水敏性的微观机理研究将成为一个重要方面。吸水率为评价固化黄土内部物质成分变化引起孔隙结构改变的重要指标,通过不同胶固比的固化土的吸水率变化,结合XRD、SEM对改性糯米灰浆固化黄土的微观作用机理进行分析。研究结果表明:胶固比为0.45的固化土,经过28 d养护后,饱和吸水率下降到18.71%,且XRD分析同样发现0.45胶固比的固化土中方解石含量增长最为明显。微观镜像中,改性糯米灰浆中的石膏和方解石晶体对孔隙进行了填充,改变了黄土原有的孔隙结构,并增强了土颗粒间的粘结。改性糯米灰浆的固化作用,使黄土原有孔隙结构和物质成分发生改变,改善了黄土的水敏性,其应用于黄土窑洞墙面的修复,将会减少由于水敏性导致的墙面病害。

The water sensitivity of loess is an important factor affecting the protection and restoration of earthen sites in loess areas.The site dominated by loess caves in the northern Shaanxi revolutionary site was caused by the water sensitivity of the loess,leading to the surface of the cavern to fall off,chalk and seepage.When the modified glutinous rice mortar is used to cure loess as a wall repair material,the study of micro-mechanism scoping to improve water sensitivity will become an important aspect.Absorption rate is an important index to evaluate the change of the composition of the substance inside the cured loess caused by the change of the pore structure.With the changing in water absorption rate of cured soil through different gum-fixing ratios,the microscopic action mechanism of the modified glutinous rice mortar solidified loess is analyzed by XRD and SEM.The results show that the saturated water absorption of the solidified soil with a cementation ratio of 0.45 decreases to 18.71%after 28 days of curing,and the XRD analysis also indicates that the content of calcite in the solidified soil with 0.45 cementation ratio is increased most obviously.In the microscopic image,the gypsum and calcite crystals in the modified glutinous rice mortar fill the pores,which change the original pore structure and enhance the adhesion between the soil particles.The curing effect of modified rice mortar changes the original pore structure,material composition of the loess and improves its water sensitivity.The application of the loess to the repair of the loess kiln wall surface will reduce the wall surface disease caused by water sensitivity.