Desiccation cracking and strain localisation response of compacted clays with varying plasticity using DIA and DIC

Desiccation-induced cracking in compacted clayey soils remains a key concern in the long-term resilience of transportation and geotechnical infrastructure. This study investigates the mechanistic role of soil plasticity in controlling crack initiation, propagation and strain localisation under controlled drying conditions. By leveraging a combined Digital Image Analysis (DIA) and Digital Image Correlation (DIC) workflow, real-time quantitative tracking of crack evolution and strain fields was achieved across a suite of low, intermediate, and high plasticity soils. The results revealed that low plasticity soils exhibited sparse, isolated cracking with limited strain localisation, while intermediate plasticity soils developed dense, highly connected crack networks with pronounced strain accumulation. In contrast, high plasticity soils produced fewer but markedly wider cracks due to concentrated deformation. The integrated DIA-DIC approach yielded consistent, physically meaningful performance zones linking soil plasticity with both morphological and strain localisation responses. The insights from this study provide a framework for optimal clayey soil selection in embankments, liners, and engineered barriers where drying-induced damage is a critical design consideration.