The Experimental Study On Specific Surface Area Of Red Clay

The specific surface area is an important physical and chemical indicators of clayey soils. The appropriate testing technology is selected in this paper after comparing the characteristics of the different testing technology of the specific surface area. Based on the red clay in Liuzhou of Guangxi region, analyzing the characteristics of the specific surface area of the red clay and its influencing factors. The main results are as follows:(1) The present study is undertaken to determine the SSA of 5 different clayey soils by the follow three methods(viz., Methylene blue method, Ethylene Glycol Monoethyl Ether adsorption method, adsorption of Glycerin) and estimate the SSA of clayey soils by the empirical formula, air-dried moisture content method. The experimental results show that, for nonswelling clay, the SSA by 4 different methods are roughly the same; But for the soil samples which contain montmorillonite measured by the EGME method are smaller than other methods. Methylene blue method has the advantage of close to the actual working state, which is quick and simple, and is a more suitable method.(2) The mainly component minerals of red clay in Liuzhou are kaolinite, illite,quartz and goethite. The mainly component soluble cationic of red clay in Liuzhou are Na+, Ca2+and Mg2+. The specific surface area of red clay ranges between 48.93 m2/g and 61.17 m2/g. The soil located at the surface layer within the scope of 2-3m, where the content of quartz is high, while the content of kaolinite and illite clay minerals is low. Meanwhile, the content of soluble cationic such as Ca2+and Mg2+ is relatively low, so its specific surface area is minimal. Due to the MB adsorption method is conducted in saturated state, so the specific surface area of red clay in Liuzhou which is determined by the MB adsorption method is bigger than the BET adsorption method.(3)The concentration of hydrochloric acid solution is configured at1.5%, 3.0%and 4.5%, respectively. Then the red clay in Liuzhou is soaked by hydrochloric acid solution for 2d, 7d and 14 d. It is found that, with the concentration is increasing and immersion is prolonged, the specific surface area of red clay becomes smaller and shows a tendency to slow down. The red clay is soaked by the different concentration level of hydrochloric acid solution for 2 days, then the specific surface area reduces up to 30 percent. Due to the decrease of the specific surface area is associated with the free iron oxide which is dissolved by acid, the free iron oxide itself loss its specificsurface area more than the increase of the specific surface area caused by the increase of clay fraction of soil, leading to the specific surface area of the red clay showing a decreasing trend overall.