Black cotton soil is spread all over the entire area in Maharashtra and some parts of Gujarat, Madhya Pradesh, Karnataka and Andhra Pradesh. Black cotton soil have the characteristic to swelling or shrinking with the change in moisture content which affect the pavement base course and structural elements. For stabilizing expansive soil the UCS, SPT, CBR tests are carried out with the addition of Stone Powder (8% and 16%) and Polypropylene fibers (0.8%, 1.6% and 2.4%). Tests are carried out for determining the compressive strength of soil is increasing with the increasing in admixtures.