INCLUSION OF COCONUT COIR FIBER IN SOIL MIXED WITH COAL ASH

Abstract

An experimental study is conducted on local soil i.e. silty sand (SM) mixed with varying percentage of coal ash and coconut coir fiber. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests are conducted on the soil mixed with coal ash/coir fiber/ both. The percentage of coal ash by dry weight of soil is taken as 20%, 30%, 40% and 50%. A significant increase in UCS and CBR value is observed for addition of 20% of coal ash in the soil.UCS value is maximum (1.81 kg/cm 2 ) for 20% coal ash mixed with soil. The unsoaked and soaked CBR values as 10.5% and 5.6% increase to 27.7% and 14.6%, respectively. Rate of increase in CBR values decreased after further addition of coal ash beyond 20%. Randomly mixed coconut coir fiber is included in optimum soil-coal ash mix (i.e. 80% soil and 20% coal ash) and varied as 0.25, 0.50, 0.75 and 1.0%. UCS value increases substantially with inclusion of coconut coir fiber in soil - coal ash mix. The optimum percentage of soil-coal ash-coir fiber mix is arrived at 79.75:20:0.25 (by weight). Adding of these waste materials (coal ash + coconut coir fiber) results in the increase strength of soil and less thickness of pavement due to increased CBR of mix and hence saving of the stone aggregates in base and sub-base course for sustainable development in construction of highway.