Stabilisation of expansive soils using synthetic hair fibre

Abstract

Expansive clay soils pose significant challenges to civil engineering infrastructure due to their high shrink swell behaviour, which often leads to structural instability, cracking, and costly repairs. Traditional stabilization methods such as cement and lime treatment, while effective in some contexts, are frequently expensive, degrade the environmental, or ineffective under unsuitable geochemical conditions. Other stabilisation methods have also been employed, such as natural and synthetic fiber reinforcements like coir, jute, and geotextiles are widely used. Other emerging methods include enzyme treatment, geopolymers, and electrokinetic stabilisation for improved performance. The improper disposal of synthetic hair fibre a waste product from salons possesses an increasing challenge to the environment, with 9,000 to 12,000 tonnes of waste generated in Uganda alone annually by the beauty industry. This study investigated the use of synthetic hair fibres as a sustainable and low-cost stabilising material for expansive clay soils. Physical and mechanical tests, alongside crack analysis using digital image processing and MATLAB R2025a software were conducted. Expansive clay samples were stabilised with synthetic hair fibres at a fixed amount of 0.5% by dry weight, with fibre lengths ranging from 2 cm to 16 cm. Key tests, including Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and swelling potential, were conducted. The results showed a 56% increase in UCS, a 300% increase in CBR, and a notable reduction in swelling, particularly with fibre lengths between 6 and 8 cm. The research shows that synthetic hair fibre is a viable alternative for stabilizing expansive clay soils, offering both geotechnical benefits and a sustainable approach to managing synthetic hair waste.