Effect Of Rice Husk Ash On Unconfined Compressive Strength Of Jamshoro Shale

Abstract

This study investigates the effect of rice husk ash (RHA) on the unconfined compressive strength (UCS) of Jamshoro shale in a compacted state. Shale samples were blended with RHA at 0%, 2%, 4%, 6%, 8%, 10%, and 12% by weight, compacted at optimum moisture content, and tested for unconfined compressive strength, undrained shear strength, and stress-strain modulus. Results showed that the unconfined compressive strength (qu) increased progressively from 6.93 kg/cm² at 0% RHA to 11.83 kg/cm² at 12% RHA, representing an increase of approximately 70.7%. Undrained shear strength (Su) followed the same trend, rising from 3.465 kg/cm² to 5.915 kg/cm², while the stress-strain modulus (Es) increased from 1.50 kg/cm² to 2.20 kg/cm², an increase of approximately 46.7%. These findings indicate that RHA is an effective additive for enhancing the strength characteristics of Jamshoro shale, likely due to pozzolanic reactions between the RHA and the clay fraction of the soil, improving its suitability for use as a subgrade or embankment material in highway construction.