Microstructure of a swelling clay treated with lime

Lime is used successfully to improve the mechanical properties of clays. In this study, hydrated lime was chosen to limit the swelling of a highly plastic Ca-montmorillonitic clay. This paper is aimed to obtain a coupled micro-macroscopic data on the behaviors of lime-stabilised swelling materials. The constant volume swelling pressure measurements was carried out using a new developed apparatus. Tests using compacted lime-treated and untreated samples with different initial moisture contents, dry densities, percentages of lime were carried out to evaluate these effects on swelling capacity. Then, textural and structural changes (particles organization, pore spaces from nm to mum) were studied using X-ray diffraction and mercury porosity intrusion tests. The results obtained demonstrate the positive effect of lime on the swelling pressure (up to 95% reduction). Changes induced at the microscopic level were detected and analysed. They provide a clear explaination of the differences in macroscopic behavior induced by the studied variables.