Research On Measuring Method Of Specific Surface Area And Bound Water Based On Microwave Drying Method

Because of the wide application prospect of unsaturated soil mechanics in many engineering fields,SWCC has been the focus of many experts and scholars at home and abroad.But the existing SWCC basic testing methods have some disadvantages such as expensive cost,harsh test conditions,long time consuming and discrete data.Therefore,based on the characteristics of uniform dehumidification and easy control in the microwave drying process,this paper attempts to explore the law of soil water change and microwave energy change from the perspective of microwave drying,so as to reveal the quantitative law of clay specific surface area,combined water content and energy change in the process of clay drying,The method of measuring the specific surface area and the combined water of clay based on the microwave drying curve is proposed.1.the dynamic model of microwave drying of clay is deduced theoretically.The relationship between water content and drying time is revealed.The characteristic parameters of the model are related to the intake value,residual water content and pore ratio of the sample;2.in this paper,a microwave drying method is designed based on the mixture of kaolin and calcium montmorillonite.The experimental results show that the microwave drying dynamic model can describe the microwave drying process of the mixture better;3.a new method of specific surface area estimation-"K value method" is proposed.Taking granite residual soil and Xiangjiang clay as an example,the experimental results obtained by k-value method and ethylene glycol ether method are compared and analyzed.The conclusion that "K value method" is suitable for granite residual soil but not suitable for dry soil burning in Xiangjiang clay heating process is obtained;4.a microwave dehumidification test method with approximate dehumidification energy is designed,and the experimental research is carried out with kaolin as an example;The results show that the quantitative analysis of five dehumidification stages of kaolin by "five stages" is in accordance with the objective law.Through the comparative analysis of the results of different methods,it is concluded that the combined water content determined by the five-stage method has a high accuracy.This paper presents a method of estimating specific surface area of kaolin by microwave drying method based on the assumption of equal step dehumidification energy and a new method for determining kaolin bound water by microwave dehumidification energy control.The experimental results show that the former can meet the needs of practical engineering for the measurement of general cohesive soil specific surface area without high precision;The latter can be used to determine the content of kaolin adsorbed water.The two methods open a new field of vision for the study of the specific surface area of clay minerals and the study of the micro characteristics of combined water,which also have important enlightenment on the evaluation of clay engineering properties and the study of soil engineering,which is worth further research.