Subgrade soil stabilization by using demolished concrete waste and recycled plastic polymers

Abstract

Long term performance of pavements depends upon the stability of its underlying soil. There are various methods of stabilizing subgrade soil which are both expensive and labour intensive. However, based on literature review, it was found that using demolished concrete waste and recycled plastic polymer beads in order to enhance the properties of the weak soil and making it suitable for engineering purpose can be a low cost and effective alternative for soil stabilization. Also, the current annual rate of generation of construction waste is 1183 million tonnes worldwide in which 11.4 to 14.69 million tonnes per annum is generated in India. Therefore, reusing demolished concrete waste and recycled plastic polymer beads as subgrade stabilizer proves to be environment friendly too. So there is a need to transform ineffective waste materials into effective subgrade materials. In this study, the initial properties of unstabilized soil sample (such as maximum dry density, optimum moisture content, CBR value and unconfined compressive strength) and the initial properties of waste concrete aggregates (such as specific gravity, moisture content, bulk density, aggregate impact value and aggregate crushing value) are determined. Then the unstabilized soil is mixed with varying proportions of waste concrete aggregates and recycled plastic polymer beads and its CBR values, maximum dry density, optimum moisture content and unconfined compressive strength is determined and compared with that of unstabilized soil, based on which the optimum dosage of stabilizer is suggested.