The major difficulties of placing foundation on expansive soils are the swelling properties of them. We all know that expansive soil mostly contains clay particles and we have discussed in many posts about Montmorillonite and kaolinite. Now our aim is to provide an idea to reader about the calcium treatment for such clay particles.
The purpose of treatment of expansive soil with calcium oxide is the change in its mineral structures and a suitable change in mineral structures leads a expansive soil to behave better as founding bed for building structures. In the process of treatment lime results a chemical reaction of cation exchange where the ions attached to crystal of clay are substituted by the positive atoms in the solution. Calcium oxide provides a cementing agent in the expansive soil which renders a strong and firm soil. The smaller particles are get together to form larger particles as the positively charged particles react with opposite charged particles.
Calcium oxides treatment thus results a treated expansive soil of greater strength and low susceptible to shrinkage and swelling process. By this the major limitation of expansive soils are removed. The expansive soils spread all over the world and results many difficulties to foundation. In United States many structures are suffering by this soil. In India this soil is found mostly in the form of black cotton soil. We have published many posts about black cotton soil and with its suitable foundation guidance. In Africa there have also the same problem of black cotton soil.