Various stabilisers have been employed to improve soil qualities in road applications. However, these were mostly introduced by partly substituting soil with cement or lime. The purpose of this study is to investigate soil engineering qualities by using fly ash as a binder in addition to Terrasil. To make the soil combinations, soil was mixed with varied quantities of fly ash and a chemical called Terrasil. The engineering performance of the stabilised soil was evaluated using Atterberg limits, maximum dry density (MDD), optimum moisture content (OMC), unconfined compressive strength (UCS), and California bearing ratio (CBR). The experimental results showed that adding the chemical Terrasil to the soil improves UCS and CBR parameters. The ultimate purpose of this study is to assess the durability of using a chemical for ground surface improvement, as well as the ideal amount of the stabiliser for maximal strength. Furthermore, Unconfined Compression Strength (UCS) experiments on soil combinations indicated the optimal chemical dose that corresponded to peak strength, for a 28-day cure period. After 7 and 28 days of curing, silty soil combined with 15% fly ash and Terrasil, showed increase in UCS value by 182.85% and 363.71%, respectively. CBR value after treatment came out to be 8.73% and 6.08% for unsoaked and soaked cases, respectively.