The geotextile industry research and development is growing at a fast rate and new products of variable specifications are now available for earthworks and design engineers. The polypropylene fiber material is non-biodegradable which can stand aggressive chemical exposure when placed along with soil media. This research is conducted on a polypropylene fiber reinforced soil treated with chemical admixture in order to study the interlocking mechanism and to study the extent of improvement on their tensile behaviour. Locally available plastic clay was selected for this investigation. The extent of improvement by the polypropylene fibres inclusion on the tensile behaviour was evaluated by carrying out a series of Brazilian tensile strength tests. The dominant mechanism responsible for the increase in tensile strength properties has been proposed. The effect of various geotechnical parameters like grain size distribution, density and moisture content on the tensile strength improvement has been discussed. The study shows that the addition of polypropylene fibers alone to highly plastic clay will not suffice the tensile strength requirements. The polypropylene fibers when added with lime of 6% can improve the tensile strength by further 13 to 28% depending on the dose or fiber content.