Expansive clayey soils at the subgrade level of roads and highways in different cities can affect the performance and durability of pavements. This increases the need for maintenance and conservation work, leading to higher operating costs. Traditionally, clayey soils are stabilised by adding lime or cement. However, the handling and use of these materials are restricted in some Latin American countries due to illegal drug production, and obtaining high-quality materials from distant sources can be impractical. The goal of this study is to determine the effectiveness of incorporating fibres in improving the performance of expansive clayey subgrade soils. To achieve this goal, resilient modulus tests and measurements of compacted soil expansion were performed. Two types of fibres were selected for this study: natural Ichu fibre, which is common in the Peruvian Andes, and polypropylene fib...