Mitigation of desiccation cracks in clay using fibre and enzyme
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ORIGINAL PAPER
Mitigation of desiccation cracks in clay using fibre and enzyme Yuekai Xie 1 & Susanga Costa 2 & Limin Zhou 3 & Harpreet Kandra 4 Received: 9 September 2019 / Accepted: 30 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Formation of cracks during desiccation is a natural phenomenon in expansive clay. Mitigation of desiccation-induced cracks is highly beneficial for increasing the life span of geo-infrastructures particularly in hydraulic barriers. Improvement of soil properties using additives is a key method in controlling desiccation crack formation and their influence. This paper presents experimental results for an expansive clay modified with nylon fibre and an enzyme-based product. A series of desiccation cracking tests were carried out with varying fibre contents and a constant enzyme dosage. Three-point bending beam tests were performed to evaluate tensile strength of the modified clay. The additives, fibre and the enzyme were able to alter the crack patterns significantly thereby alleviating the effects of cracks. Furthermore, the addition of enzyme alone increased the tensile strength by about 50% while the combined effect of both fibre and enzyme increased the tensile strength by approximately 100% compared with untreated soil. Based on measurement of crack patterns and other properties of the modified clay, the investigation suggests the potential for the fibre-enzyme addition to mitigate desiccation cracks. Further work needs to be carried out to determine optimal dosing requirements for each additive and investigate the effects of potential interactions between the fibre and enzyme. Keywords Desiccation . Fibre . Enzyme . Tensile strength . Clay
List of notation ΔTfibre Tensile strength gain due to fibre addition Ca Adhesion of fibre to soil fc Fibre content wcr Cracking water content σn, f Normal stress acting on fibre A, B Constants δ Friction angle between fibre and soil
* Susanga Costa [email protected] 1
School of Engineering & IT, University of New South Wales, Canberra, ACT, Australia
2
School of Engineering, Deakin University, Geelong, Victoria, Australia
3
Faculty of Construction and Environment, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
4
School of Science, Engineering & IT, Federation University Australia, Churchill, VIC, Australia
Introduction Clay soils are an abundantly used construction material with one of the major applications being the construction of landfill liners and other environmental barrier systems. The primary purpose of these geo-structures is to contain waste and the degrading components (leachate). Almost all of these structures are exposed to natural environment and are subjected to seasonal climatic and weather changes. Compared with other engineering materials such as steel, concrete, and timber, clay soils are susceptible to undergo large strains due to atmospheric changes. Stresses resulting from restrained shrinkage in clay soils during desiccation can lead to desiccation
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