Shrinkage cracks of bentonite-zeolite mixtures

Nanyang Technological University, School of Civil and Environmental Engineering, 50 Nanyang Avenue, 639798, Singapore

^* Corresponding author: cecleong@ntu.edu.sg

Abstract

Bentonite is commonly used in geosynthetic clay liner (GCL) as well as compacted clay liner (CCL) for containment facilities such as sanitary landfills due to its low permeability. Bentonite experiences significant shrinkage on drying, leading to the formation of desiccation cracks and increasing the likelihood of contaminant leachate from the landfill. Adding granular materials such as fine sand to bentonite canreduce shrinkage and hence shrinkage cracks. Recently, zeolite has been suggested as another possible additive to reduce be shrinkage cracks in bentonite. Zeolite has additional benefits of being able to adsorb heavy metals and when enriched with silver, zinc, or copper, it can function as a biocide. The objective of this paper is to present the results of a study on shrinkage crack formation of bentonite-zeolite mixtures during drying. The evolution of shrinkage cracks of the bentonite-zeolite mixtures on drying was studiedusing image processing. The results show that desiccation cracks are at a minimum when the zeolite content is between 15% and 20%. The finding is useful to design more efficient GCL or CCL when zeolite is incorporated into the bentonite layer.