Expansive soils, which are generally termed as problematic soils, cause swelling and shrinkage resulting in significant damage to the structures constructed on them. In this study, an attempt is made to know the effect of Road Building International Grade 81 (RBI Grade 81) on strength characteristics of expansive soil. RBI Grade 81 has a wide range of response spectrum. Response spectrum is the range of soils for which a particular stabilizer can be used. A wide range of tests, such as Atterberg limits, compaction, unconfined compressive strength, and California bearing ratio, were conducted on expansive soil and expansive soil treated with various percentages of RBI Grade 81. The results indicate that RBI Grade 81 is effective in improving engineering properties of expansive soil.