INCORPORATION OF WASTE POLYETHYLENE TEREPHTHALATE INTO CONCRETE USING STATISTICAL MIXTURE DESIGN

This paper investigated the incorporation of waste Polyethylene Terephthalate (PET) into concrete as a replacement for natural fine aggregate and found an optimal combination of components that produces a useful concrete product. Six components were considered: cement, water, coarse aggregate, fine aggregate, super plasticizer, and waste PET. A total of 31 mixes were prepared based on a statistical mixture design approach. The responses of these mixtures were workability, compressive strength, and splitting tensile strength. The waste PET was first reduced in volume by shredding and then combined with the rest of the components. The responses from the experiments were statistically analyzed and a model fitted to each response. Linear models were found to fit the responses best. Using the desirability function approach, four optimal options were selected and then verified in the lab by comparing the experimental with the predicted values. Except for one, all the values fell within the 95% prediction interval. The option that best fulfilled the workability and strength requirements was found. The average response values obtained with this combination were:(1) compressive strength of 23.8 MPa; (2) slump123mm, and (3) splitting tensile strength of 3.33 MPa. This mix can be used in basements foundation walls or slabs, inside buildings not exposed to freezing temperatures. It is recommended that future work should consider method of mixing, time of mixing, volume of mix, curing conditions, and other responses to further understand the characteristics of incorporating waste PET into concrete.