Date of Award

Spring 2003

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering

Committee Director

Isao Ishibashi

Committee Member

Duc T. Nguyen

Committee Member

Resit Unal

Committee Member

Jim X. Zhang


The purpose of this research is to study the possibility of recycling discarded automobile tires as a lightweight construction material by injecting expanded polystyrene (EPS) into the hollow space of the tires. The observation from compression tests on used tires revealed that the tread wall of these tires bent toward their own center. This inward deformation should provide confining stress to the contained EPS, and thus the compressive strength of EPS-tire composite was expected to be higher than that of EPS.

To produce EPS-filled tire prototypes for this study, EPS type II, with density of 24 kg/m3, was injected into hollow space of used tires. These EPS-tire prototypes had some air pockets unfilled with EPS inside. The air pockets were filled by injecting sealant foam made of polyurethane intermediate available in hardware stores. Compression tests on individual and stacked EPS-tires were carried out in the laboratory. Result from compression tests revealed that the yield strength of EPS-tires was higher than that of EPS, but with a lower elastic modulus. The laboratory compression tests were simulated by using a computer program UDEC, which was based on the distinct element method (DEM). The two-dimensional UDEC, along with a three-dimensional finite element program KENLAYER, were used to simulate plate load tests on subgrade soil covering EPS-tire embankment to find modulus of reaction on top of subgrade, which is needed for the pavement design.

It appeared that the EPS-tires studied in this research were relatively soft when compared with conventional embankment materials for highway embankments. The cost analysis shows that systems of EPS-tires are more expensive than other treatment methods for soft ground problems at present mainly due to the cost of handling the tires during the manufacturing process. However, if the manufacturing technique were improved, and the manufacturing cost were reduced due to mass production, a system of EPS-tire embankment would be an attractive alternative to solve the issue of used tires disposed in landfills.


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