Quantification of desiccation cracking and strain localization in lime-treated compacted expansive soils using DIA and DIC

Abstract

The present experimental study is focused on quantifying the initiation and propagation of desiccation cracking and strain localization in lime-treated compacted expansive soils subjected to controlled temperature and relative humidity conditions. Two bench-scale experimental setups were designed and developed in this study to capture the desiccation cracking and strain localization in soil specimens using digital image processing (DIA) and digital image correlation (DIC) techniques, respectively. A Python program was also developed for autodetection of optimum threshold intensity for crack segmentation, which considerably reduced the chances of noise in DIA and allowed accurate batch processing of multiple images. An open-source software Ncorr was used for two-dimensional DIC analysis to obtain strain localization plots during the desiccation process of soil. The effectiveness of the lime treatment technique for the stabilization of expansive soil was evaluated by considering the major issues of expansive soils such as swelling, shrinkage, unconfined compressive (UC) strength, and desiccation cracking. The results revealed that the lime treatment was ineffective in controlling the desiccation cracking of expansive soil. Only a small percentage of lime (2% or less) was found to slightly reduce the desiccation cracking. However, such small quantities of lime were not found enough to fully sway the swelling and shrinkage nature of the soil. A significant change in the crack pattern was observed in specimens treated with 3% or higher amount of lime. The total length of cracks increased up to 75% due to the addition of 6% lime compared with untreated soil. Similarly, more localized deformation zones were observed in strain localization plots of specimens treated with 3% or higher amounts of lime.