Effect of Lime on California Bearing Ratio (CBR) of Soft Soils

Soft soils are well-known for their weak strength, compressibility and are considered of
having poor engineering properties. These soils induce more construction problems to
remove and replace the unsuitable soil. However, past researches had discovered that
these soft soils could be treated and be made suitable for construction usages. One of the
methods is through soil stabilization, where one or more soil properties is altered by
mechanical or chemical means. Utilizing chemical stabilization, lime was added to the
soil to improve the soil engineering properties. The addition of lime to a soil has a
pronounced effect on its physical and chemical properties. Two main changes take place
when lime is added to soil; the physical characteristics of the soil are altered and
cementitious compound form resulting in some bonding of particles. The main research
parameter is onthe strength gain behaviour, or California Bearing Ratio (CBR) of the soil
upon lime addition. Initial classification tests were conducted on the soil to obtain its
initial characteristics and establish its initial value of strength parameter (CBR). CBR
tests were conducted on the natural soil as well as with the addition of 2%, 3%, 4% and
6% lime to determine the strength development and swelling effects of the soil under
soaked conditions. The treated soil was found out to have increasing CBR value with
increasing lime content while the swelling behaviour decreases with respect to the
amount lime used. From the testings, 3% of lime was found to be the optimum lime
content in treating the soil.