Properties of swelling soil improved using mixture of polyethylene with silica fume and cement kiln dust

Abstract

Expansive soils (also known as shrink/swell soils) are encountered in various regions of the world. The behavior of this type of soils is quiet complex. As they fall in the category of ‘problematic soils’. Swelling and shrinkage in soils occur as a result of the seasonal variations in climatic conditions which affect the water retention in soils. Climate change prediction shows that these problems may get worse in the future. This leads to more interest in this subject during the last few years, with an increasing attention, in experimental investigations, modeling, and field investigations. In order to reduce the pollution and to keep the environment clean and sustainable, waste and recycled materials are used in the current study to improve the undesirable characteristics of expansive soil samples in the lab. Therefore, several laboratory tests have been carried out to proof that using of a significant by-product material of the cement manufacturing process the cement kiln dust (CKD) is contributed in improving the properties of an expansive soils, silica fume material (a waste industrial material) is also be useful in reducing the effect of the shrink-swell in soils, and finally using a high density polyethylene polymer (PEHD) is showed a significant decreasing in swelling deformation and increasing in the unconfined compressive strength with some other considerable changes in the previous soil properties. The Polyethylene polymer may used to enhance the behavior of expansive soil and reduced the most common problem related to this soil (swelling potential). As well as, silica fume could be effectively used to improve the properties of expansive soil with specific limits. Therefore, the main aim of this study is to observe the ability of CKD with silica fume and polyethylene polymer in improving the characteristics of expansive soil. The results shows that using additives 10% of CKD, 5, 10, 15% of silica fume, and 5, 8, 10% of PEHD decreased liquid limit and plasticity index of an expansive soil, increased its plastic limit values, and also contributed in stabilizing the expansive soil by significantly reducing it swelling ability. The liquid limit and plasticity index are reduced from 88% to 53.2% and from 67.8% to 29.6% respectively by adding 10%CKD, 10%Silika fume and 10% of PEHD. And the swelling potential is decreased from 21.23% to 2.1% by adding these additives.