A new mixing technique for randomly distributed fibre-reinforced expansive soil

In the state of Gujarat, India, a significant part of the area is covered by expansive soil deposits. The swelling and shrinkage characteristics of expansive soil as a result of wetting and drying cause problems for safety and/or performance of structures. The concept of reinforcing soil with fibres, resulting in a randomly distributed fibre-reinforced soil (RDFS), has been studied in significant details, especially for reinforcing granular soils. Studies on fibre-reinforced expansive soils as reported in the literature are very limited. One of the major problems in the study of fibre-reinforced expansive soils is how to mix fibres uniformly. Therefore, the main objective of this paper is to study the available mixing methods, assess their suitability and develop a new mixing technique, which will be cost-effective for mixing fibres with expansive soil, especially in developing countries. In the present study, a surface modification method with cement has been proposed, where the waste tyre fibres (WTFs) were coated with cement to improve the bonding between fibres and clay minerals. The effect of this modification on the strength property of reinforced soil has been examined with unconfined compressive strength analysis. The results show that the shear strength between cement coated fibres and soil is significantly higher than the shear strength between fibres and natural soil