Influence of Initial Moisture Content on the Slaking Features of Expansive Red Clay

This paper is aimed to characterize the slaking features of the expansive red clay under the different initial moisture content condition. The slaking experiments of weak expansive red clay were carried out in laboratory. The slaking difference was explained by video photographs, optical microscope photograph, and scanning electron microscope images. The slaking and fractal features of expansive red clay were analyzed under the different initial moisture content of 3%, 8%, 13% and 18%, respectively. The results show that the slaking time is earlier with its lower initial moisture content. The slaking rate is also increased with decreasing initial moisture content. The fissure development degree of expansive red clay in slaking test has presented rapid increase, slow increase, and stable trends characteristic with the increasing soaking time. Under the condition of minimum moisture content in 3%, the maximum fissure development degree can reach 4.6. The index value of maximum fissure width increased in the first half of immersion time, and oscillatory decreased in the second half of immersion time. Macroscopically, the slaking of expansive red clay is more likely to occur under the condition of low moisture content, which is mainly due to the scattered agglomeration units and high percentage of micropores in the expansive red clay. The fractal dimension is positively correlated as a quadratic function with the initial moisture content, which resulted in the slaking more complete and slaking time shorter with lower fractal dimension.