In this experimental study, compressive strength and resistance to sodium sulphate attack of concrete incorporating recycled ceramic tiles (RCT) as fine aggregate were investigated. RCT was used as partial replacement for river sand at four levels (0%, 33%, 66%, 100%). Samples for sulphate resistance tests were immersed in 5% Na2SO4 solution for 180 days after they had been cured under water for 28 days, and were monitored for change in physical appearance, mass change and loss of compressive strength. From experimental results, RCT was found to be capable of producing light weight concrete compared to river sand. The results showed increase in compressive strength as the level of RCT content increased. On resistance to sulphate attack, sodium sulphate seems not to attack C-S-H bond which is produced in excess in RCT concrete, rather it attacks calcium hydroxide and calcium aluminate which are produced in equal amounts for both RCT and control samples. Hence, RCT might not play much direct role in concrete’s resistance to strength loss due to sulphate attack. However, the residual compressive strength of the RCT samples after the attack was seen to be much higher than that of the control samples because of their initial higher strength before the attack. This shows that RCT can improve the properties of concrete when incorporated as fine aggregates.

The usage of waste plastics in the form of eco-bricks for the construction of buildings is gradually gaining traction. However, the performance of eco-brick masonry walls is not sufficiently known, and the process of setting up experimental rigs for the conduct of compressive strength test of masonry are usually cumbersome and expensive. This study investigated the compressive strength performance of eco-brick masonry walls and developed a predictive model for evaluating the strength of eco-brick masonry walls. Waste polyethylene terephthalate (PET) bottles were physically recycled and utilised to manufacture four samples of eco-bricks, strength grades 40.5, 21.02, 13.52 and 3.05 N/mm² using stone dust, sharp sand and laterite at predetermined moisture contents. The eco-bricks were laid with seven grades of mortar to build 54 eco-brick masonry prisms. A quasi-static compressive loading test was carried out on the masonries, and predictive models were developed using multiple non-linear regression. The study found that eco-brick masonry prisms supported large loads and failed due to the propagation of tensile cracks and debonding of the units. The study also found that the compressive strength of eco-brick masonry is a power function of the compressive strength of eco-bricks and the mortar used for the bonding. It was determined that the mean ratio of the expected to experimental prism strength was 1.002. The mathematical model developed in this study for predicting the strength of eco-brick masonries can significantly evaluate the compressive strength of eco-brick masonry.