Comparing Consistency Limits of Black Cotton Soil with Cement Waste Dust and Wood Shaving Ash

Abstract

In the field of civil engineering, soil has to play a prime role right from planning a structure to the end of life of that structure. But some of the soils do not offer that service which a civil engineer wants to get. Shrinking in dry state and swelling in wet state, is the well-known proved proverb for black cotton soil. In Saurashtra, southern part of the zone has such soils with problem of volume change in absence and presence of water. In this research, an experimental study is carried out on black cotton soil of local area in Saurashtra (Gujarat) with cement waste dust and wood shaving ash. Consistency limits were studied with and without these two stabilizing materials. 0, 5, 10, 15 and 20% of mass of soil sample were considered for both the stabilizing materials in order to conclude the research study. Laboratory work was done in accordance with IS 2720 of geotechnical engineering. While comparing the stabilizing materials, cement waste dust shows parabolic change in the value of liquid limit from 59 to 39% and plastic limit from 34 to 27% with the crown value of 31 and 22% respectively. Hence, final reduction in plasticity index from 25 to 9%. On the contrary, wood shaving ash shows gradual increment (within experimental limitations), in the value of liquid limit from 59 to 73% and plastic limit from 34 to 55%, concluding with reduction in plasticity index from 25 to 18%. As far as comparison is concerned, cement waste dust is more suitable than wood shaving ash, as cement waste dust not only reduces the plasticity index (with respect to unstabilized soil), but also controls the liquid limit and plastic limit during the tests due to pozzolanic activity.