Shrinkage behaviour of landfill clay liner materials in dry zone

Abstract

Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to infiltration of leachate into ground during the rainy season. Therefore, in this research study, shrinkage behaviour of expansive soil available in dry zone of Sri Lanka, which is used to develop compacted clay liners, were evaluated using laboratory desiccation plate tests. Circular desiccation plates with different thicknesses were used for the experiments. A series of tests have been carried out with unamended soil and soil amended with different percentages of bentonite. Further, shrinkage behaviour was studied by amending oleic acid and coconut coir fibers into the soil. Digital image processing technique has been used to determine the Crack Intensity Factor (CIF). Crack initiation time under different configuration was recorded. Based on visual observations, it can be seen that all samples produce predominantly orthogonal crack patterns leading to sub division of crack area in to smaller cells. Higher desiccation rate was observed for smaller thickness of soil specimen. In addition, higher CIF was recorded for the bentonite amended soil. It was noted that shrinkage cracks can be controlled by amending soil with coconut coir fibers.

Investigation into the cracking potential of different composite liners under wetting-drying cycles

“…ber can result in a decrease in the CIF value (Priyankara et al, 2016). Adding coconut ber to composites containing expansive soils can reduce the development potential of the soil.…”

“…Furthermore, a 5% coconut ber mixture was used in this study. This percentage was chosen following Priyankara et al (Priyankara et al, 2016), who examine variations in CIF using 10% bentonite and 5% coconut ber resulting in a reduced CIF value due to the presence of coconut ber breaking the soil specimen into reduced lumps. A total of six variations were used which are presented in Table 2.…”

Evaluating Coconut Fiber and Fly Ash Composites for Use in Landfill Retention Layers

“…In this study, the incorporation of additional materials, such as coconut fiber, was able to control shrinkage cracking; therefore, coconut fiber was selected as a composite material to determine the optimal blend of materials that could be employed in the landfill leachate retention layer system. According to Priyankara et al (2016), the incorporation of coconut husk into soil mixtures reduces the plasticity properties of the soil, and soil volume changes caused by cracks can be minimized and controlled [16]. In addition, conducted a similar study using fly ash, bentonite, and 1% quicklime at bentonite concentrations of 0% (FAB0), 15% (FAB15), 20% (FAB20), and 25% (FAB25) [17].…”