Conversion of auxiliary wastes for production of masonry bricks: towards conservation of natural clay

The concerns about the effect of climate change due to high energy consumption and dwindling natural material for the production of bricks and other construction materials have given rise to this study. To address these concerns, polyethylene terephthalate (PET) waste bricks (PWB) were produced using scrap PET and foundry sand in different proportions of 20%, 30%, and 40% by dry mass of the foundry sand. The durability and strength properties of the fabricated PW bricks exposed to acid attack were investigated and results were compared to conventional clay bricks. The load-bearing capacity of the bricks under compression and tension was also evaluated in compliance with South African National Standard SANS 227. Scanning electron microscopy (SEM) tests were performed to understudy the impact of acid exposure on the microstructure of PW bricks also to track the factors responsible for strength developed in these bricks. The test results revealed that 20% and 30% inclusion of melted PET waste rendered a considerable increase in tensile and compressive strength values to a limiting ratio of 30: 70 blends of plastic and foundry sand, beyond which strength modulus decreased. The tension and compression strength resistance of the PET waste bricks on average recorded an appreciable strength of 1.5 - 2 times higher than that of the commercially fired clay bricks that were used as the control. The exposure to acid attack did not affect the PW bricks whereas, it triggered a decrease in strength when compared with the conventional clay bricks.