Effect of partial replacement of aggregate with granulated polyethylene terephthalate (pet) on compressive strength of concrete

Abstract

This paper is aimed at the development of appropriate combination of composite materials such as cement, aggregates and inclusion of Polyethylene  Terephthalate (PET) in varying proportion in order to determine the optimal measure for the optimal strength. The study also, investigated the effect of  PET aggregate on the compressive strength of concrete. Mix design targeting grade 25 concrete strength, using the Department of Environment (DOE)  approach was adopted. Five different concrete samples were prepared accordingly, using natural aggregate as control mix and four others which consist  of PET aggregate as partial replacement of fine aggregate at 5%, 10%, 15%, and 20% ratios respectively. The recycled fine aggregate (PET) was processed  from bottle water waste, it was crushed, pressed and processed into finely material having river sand resemblance i.e., well distributed within sieve sizes  of 0.075 and 2.00. The batching was done by weight. Cubes specimens were prepared, cured for 7, 14, and 28days and tested for compression. The  results of the tests were analyzed statistically using regression method (Mintab) to establish optimal strength require mixture. The results and analysis  established that there were reduction in compressive strength of the concrete containing PET aggregate and reduction rates increased with increase in  the amount of PET inclusion in the concrete. The compressive strength values for 5%, 10%, 15% and 20% replacement of sand with PET at 28-day were 29.70N/mm2 , 25.95N/mm2 , 24.28N/mm2 and 23.23N/mm2 respectively. When compared with the control concrete specimens with an average value of  33.08N/mm2 gave 11.38%, 27.48%, 36.24% and 42.40% reduction in strength respectively. It was recommended that, though, the use of PET aggregate in  the production of concrete does not have significant appreciable effect on the concrete strength, its use will protect the environment and as well help  to conserve natural resources used as materials in production of concrete elements which currently undergo excessive depletion.