Investigation of the Effect of High-Purity Terephthalic Acid Obtained by Hydrolysis of PET Bottle Wastes on the Cementitious Composite Properties

Abstract

One of the effective approaches to waste polyethylene terephthalate (w-PET) disposal is chemolysis, and terephthalic acid (TPA) is preferred due to its rigid and stable structure recycling product and its rigid properties. In this study, the effect of TPA hydrolyzed from w-PET shreds on the performance of mortar was investigated. This study focuses on the evaluation of the macro- and microstructural properties of TPA–cementitious composites. Although TPA reduces the compressive strength of cement pastes, an increase of 28.8% and 21.8% in flexural strength after 28 days was achieved using 2.5% and 5% TPA, respectively, compared with the strength of plain mortar. In addition, a 24.4% increase in fracture toughness at 28 days was obtained using 7.5% TPA. These results can be attributed to the better adhesion of the hydrate products to the hydroxyl groups of TPA through hydrogen bonding, and the fracture resistance of its rigid structure. Optimum dosages were determined to be 5.0%, which produced good toughness properties with acceptable compressive strength and increased hydrate content.