Plastic-bonded soils may be a sustainable method to construct more durable roadways, render soils with higher bearing capacity and liquefaction resistance, develop better waste isolation and soil retention systems, and build upon environments where conventional cements yield poor performance. This research will investigate the extent to which the strength and stiffness of a soil may be improved for applications such as these using a technique that glues the soil grains with recyclable, durable, and acid-resistant plastic. This research will study the engineering behavior of coarse aggregates fused together with polymer fines that are heated to bond the particles to make the soil mass stiffer and stronger.
Cementation-based soil stabilization techniques typically involve the use of mineral cementing agents (e.g., calcium-based). Although strong, these agents are brittle and soluble in acidic environments. Furthermore, re-cementation of de-cemented aggregates remains a challenge. The objective of this research is to explore the feasibility of a novel cementation method that uses recycled polymers and heat injection. Heat causes polymer particles in a soil mixture to soften and coalesce at the grain contacts. The polymer solidifies upon cooling, yielding a cemented soil. The result is inter-particle bonds that are non-brittle and chemically stable under a wide range of relevant environmental conditions. Moreover, re-cementation can be readily implemented by reheating de-cemented grains. The research activities will include the following scope: (1) characterize the improvement of and/or alterations in soil strength, stiffness, hydraulic conductivity, water retention, and creep behavior attained by polymeric bonding, (2) gain understanding of the role of soil and mixture properties (such as mineral composition and polymer content) on the alterations of the engineering properties, and (3) assess strength and stiffness recovery attained by reheating debonded soil (i.e., healing). Laboratory experiments conducted with custom-made and standard geotechnical testing apparatus modified with acoustic emission monitoring systems will be used to implement the research, and scanning electron microscopy will be used for micro-characterization.
