Effects of Dissimilar Curing Systems on the Strength and Durability of Recycled PET-Modified Concrete

Abstract

Since curing remains an essential parameter that directly influences concrete strength and durability, this research aimed at evaluating the effects of water, sodium chloride (NaCl), and sodium carbonate (Na2CO3) curing regimes on concrete’s strength and durability. The design mix was composed of concrete mix ratio of 1:2:4, hydrated ordinary Portland cement with a water/binder ratio of 0.50, river sand as fine aggregates, and varying percentages of heat-processed waste PET plastics and granite as coarse aggregates. The curing regimes’ performance was assessed by performing tests viz.: split tensile strength, compressive strength, and water absorption tests. The results showed that the curing regimes slightly influenced the split tensile and compressive strength of PET-modified concrete. The 5%-NaCl and 5%-Na2CO3 cured samples, compared to the samples cured in water, gained improved compressive strength values at all curing ages. NaCl curing further led to improved split tensile strengths for the 10 and 20% PET mixes. However, the water cured 20%-PET sample achieved the highest split tensile strength among PET-modified mixes after 28 days. PET-modified concretes attained water absorption percentages within the acceptable limit for normal concrete under the three curing regimes. Statistically, significant correlations and variations were established between the mechanical and durability properties assessed. The study concluded that the NaCl curing technique offers satisfactory performance at 10 and 20% PET replacement levels.