Temperature Effects on Unconfined Compressive Strength and Microstructure of Foamed Mixture Lightweight Soil Containing Flaked Polyethylene Terephthalate (PET)

Lightweight soil technology has been widely used in construction projects to solve soft ground problems. Previous work, however, has shown that the maximum interior temperature of field test bodies reaches to about 90°C. On the other hand, industrial waste disposal is an increasing problem. PET (polyethylene terephthalate) waste is now generated in vast quantities to increased consumption of drinking water sold in PET bottles. Making effective use of PET waste as a ground material may help solve the problem of its disposal. This paper describes the effects of initial high temperature curing on unconfined compressive strength and the microstructure of foamed mixture lightweight soil containing PET flake. Increase in PET-cement ratio lessened the decrease in unconfined compressive strength with increasing initial temperature. This property makes PET flake useful as a construction material. However, unconfined compressive strength decreases with increasing initial temperature at all PET-cement ratios. Observations show that the microstructure of foamed mixture lightweight soil containing PET flake have noticeable cracks if samples are cured at 90°C for 1 day; the PET flake is not completely combined with the matrix. The formation of this microstructure is the main factor of the remarkable strength decrease based on initial high temperature curing.