EFFECT OF TYPE AND PERCENTAGE OF CLAY MINERALS ON THE POZZOLANIC STABILIZATION OF CLAYEY SOILS (MACROSTRUCTURE AND MICROSTRUCTURE STUDY

The type and percentage of clay minerals in the soil as well as the pore fluid properties of double layer are the important parameter that influence on the strength and behavioral properties of the clay Soils. In this regard, clay soils are highly sensitive to changes in environmental conditions and their behavior and strength parameters will be affected by many factors such as soil disturbance, water content, loading and drainage conditions, loading rate, temperature, etc. Therefore, one of the important parameter that affect the results and efficiency of lime stabilized clay soil samples and optimum lime content (OLC) is the type and percentage of clay minerals in the clay soils. In common, methods of lime stabilization, the most effective innate factor of clay minerals in the soil is not considered comprehensively. So it has been observed that the results of various test methods are completely in conflict with each other. The accuracy of the test results depends on the simultaneous consideration of chemical and mineralogical properties of the soil. In this research, to study the micro and macro-structure of stabilization process of lime stabilized clay soil samples, different combination of bentonite and kaolinite clay samples with different percentage of lime were studied experimentally. Studied samples during the time of 7 and 28 days were cured and uniaxial test were performed on them. Then Scanning Electronic Microscope (SEM) images were done to investigate the effect of the percentage and clay mineral type on the lime stabilized clay samples. The results of this research indicate that lime stabilization increase the UCS of soft clay soils about 2 to 10 times. Also, the interaction of soil-additive, the pozzolanic reaction progresses over the time, the optimum mixture of soil and lime as well as the stabilization efficiency, significantly dependent on the type and percentage of clay minerals in the soil.