Experimental study on the effect of plastic waste strips and waste brick powder on strength parameters of expansive soils

Ethiopia has an abundance of expansive soils. This type of soil is weaker, having low strength and load-resisting characteristics in nature due to its difficulty in volume change when exposed to water. As a result, when saturated with water, the volume of such soils expands and contracts during dry seasons. In civil infrastructure construction, such soil should be removed or improved to be used as foundation soil. However, removing the soil leads to the extra costs of construction. On the other hand, improving requires increasing the stiffness and load-carrying capacity of the road by treating it with stabilizers, which help achieve low cost and good performance. This study aimed at treating such soils with waste-disposed materials to improve the soil's resistance to pressure and to reduce pollution. In this study, locally available expansive soil is treated with brick waste powder (20, 30, and 40 %) and waste plastic strips with (0.25 %, 0.5 %, and 0.75 %) percentages in weight. Disposed plastic water bottles are used. Atterberg limits, compaction, CBR, and unconfined compressive strength were performed to find an optimum percentage of mixes. Many trials were done by varying the percentages of PWS (plastic waste strips) and BP (brick powder). At the addition of 0.75% PWS and 30% BP, a significant change was observed with a considerable improvement in free swell, CBR, and unconfined compressive strength values. The study reveals plastic waste strips and brick waste powder were found to increase the strength qualities of expansive soils. This could pave the way for the use of waste materials in pavement construction while also lowering the environmental pollution.