Effect of polypropylene tape fibre reinforcement on swelling behaviour of an expansive soil

The objective of this study was to examine the influence of discrete and randomly distributed fibres on heave of an expansive soil. One-dimensional swell tests were conducted on a remoulded expansive soil with and without fibres. In this study, fibre content was varied as 0.25 and 0.5% and fibre length as 30, 60 and 90 mm. A twin semi-circular-shaped fabricated mould with a front Perspex sheet was developed for testing. Digital imaging technique was used to observe heave of the soil in both unreinforced and fibre-reinforced conditions. Displacement profiles obtained from image analysis were used for interpreting swell or upward movement profiles of the specimens. Heave observed in the digital image analysis was compared with that obtained from dial gauge readings. Reduction in heave was directly proportional to fibre content and fibre length. Reduction in heave was the maximum at low aspect ratios at both fibre contents of 0.25 and 0.5%. Test results revealed that fibre length is a key factor that influences the reinforcing effect of fibre. Discrete and randomly distributed fibres were found efficacious in reducing heave.