Problematic soils like expansive soils possess poor shear strength with high swelling and shrinkage values. Roads built on expansive soil are easily damaged because of the swelling and shrinkage property of the soil. To improve these properties of expansive soil and to increase economic and environmental benefits, stabilizing expansive soils with abundance, cheap and effective agricultural waste materials like coffee husk is becoming a recent trend. Coffee husk is a by-product (agricultural waste) of coffee, and CHA (coffee husk ash) is the resulting ash after burning it at a controlled temperature. This thesis has been carried out to evaluate utilization of coffee husk ash for improving properties of expansive soil. Expansive soils occurred in Bure agro industry park road with high expansion and shrinkage character, which is poor for subgrade construction. The laboratory sieve analysis test shows that the soil is classified under CH (highly plastic clay) and A-7-5 class of soil as per USCS and AASHTO classification system respectively. Soils under this class are generally of poor engineering use and should be stabilized. The soil was stabilized with coffee husk ash in stepped concentration of 5%, 10%, 15% and 20% by dry weight of the soil. A cycle of experiments such as Free Swell test, Liquid limit test, Plastic Limit Test, California bearing ratio (CBR) test, Specific gravity Test and sieve analysis test are carried out on expansive soil sample and stabilized soil. Analysis of the results shows the addition of coffee husk ash improved the strength and engineering property of the expansive soil. The addition of coffee husk ash reduces Free swell index, plasticity index, linear shrinkage and CBR swell with the increment of CHA content. CBR and UCS values increased with increasing CHA content. Addition of 15% and 20% CHA improved the free swell index from 115% to 23.5% and 14.5% respectively. The MDD slightly reduced from1.28 g/cm3 to 1.25 g/cm3with addition of both 15% and 20% CHA. And the OMC also slightly increased from 36.1 % to 38.2 %. The CBR value was improved from 1.5% to 14.2% and 18.5% with addition of 15% and 20% CHA respectively. UCS value also showed improvement and the effect of curing on the UCS value is also observed. Generally, from this study we can conclude that expansive soil stabilized with coffee husk ash can be used as a subgrade construction material.