Effect of lime and fly ash on load bearing capacity of expansive clay soil

Abstract

Expansive soil is a problematic soil which found in wide part of the world that has a high degree of sensitivity, nature of expansion and shrink behavior during water adding and removing this caused insufficient bearing capacity, excessive differential settlement and instability on excavation and embankment forming those conditions accelerate damage of building structure, road highway and dam. Attempt to undertake construction in such type of soil result will be bearing capacity failure, settlement problem. One of the well-known application of Lime and fly ash were improve Atterberg limits, compaction characteristics, bearing capacity and prevention of swelling problem of expansive clay that is why the main reason to select lime and fly ash in this project, both are good binding material to increase the cohesion force and shear strength of soil and assured to established rigid pavements and foundations. The mixing proportion of lime, fly ash and combination of lime and fly ash are (0%, 2 %, 4 %), (10%, 15%,20%), (2 %+10 %, 2 % +15 %, 2 % +20 %) and (4 %+10 %, 4 % + 15 %, 4 %+ 20 %) with expansive soil respectively and then explored how much it modify the characteristics of soil like maximum dry density moisture content, consistency limits, FSI, UCS and CBR value which compare to untreated soil. Lime and fly ash treated soil carried out various tests Such as Moisture content test, consistency limit, compaction test, Unconfined Compression swelling index test and California bearing ratio test then after justify weather the bearing capacity of soil is good or not . Classification of soil was determined by conducting plasticity index and swelling index tests. Effect of lime and fly ash on soil index properties were assessed by conducting Atterberg limits test, strength of soil were assessed by conducting compaction test, UCS tests and CBR test and swelling properties were checked by conducting swelling index test. Expansive clay soil were mixed with lime, fly ash and combination of lime-fly ash by replacement process of soil and then cured for 7, 14 and 28 days.