Desiccation Cracking of Kaolin Clay at Laboratory Scale

Abstract

Desiccation is the process of extreme drying that results in cracking in materials such as soils. Cracking is a complex process that has the potential to spread and penetrate deeper into the soil, which could lead to instability in earth structures like embankments. A number of desiccation tests were conducted to observe the crack behaviour of manufactured kaolin clay at laboratory scale. All samples were prepared at variation of initial water content and desiccation tests carried out using aluminium desiccation trays. Their crack behaviour was monitored at different thickness and comparison made to the samples tested on different base materials such as ceramic, steel and wood plates. The drying process, crack propagation and pattern were measured and observed daily. A digital image is captured and the crack intensity factor (CIF) calculated manually using a grid system. It was found that a sample of kaolin clay that was 5 mm thick had the highest CIF with rapid propagation and produced non-orthogonal patterns. It also discovered that the thickness of the samples, type of plates utilised and soil state at the start of the test have an impact on the formation and propagation of cracks.