Study on the effects of mixing pet and LDPE plastics on strength of plastic bonded paver blocks

Abstract

This study describes the use of different recycled plastic wastes (PET and LDPE) as potential materials used in the manufacture of plastic bonded paver blocks, with particular focus on the compressive and flexural strength. Both PET and LDPE waste plastics were collected from the variation disposal points, cleaned, shredded and ordinary lake sand was used to prepare the samples. the proportions were based on batching by mass, the waste plastics were heated and melted and thereafter mixed with pre-measured sand proportions, cast into moulds and left to cool for about 24 hours. An optimum sand percentage proportion for PET-sand was obtained as 50% and averaged with that of LDPE-sand of 70% adopted from a study by (Kumi-Larbi, et al., 2018) to obtain the optimum sand percentage sand proportion for PET-LDPE-Sand samples of 60%. Proportions of PET and LDPE were varied in different samples and resultant compressive and flexural strengths were obtained. It was observed from the results that LDPE contributed the larger chunk of flexural and compressive strength properties, PET dominant samples were generally brittle and of lower compressive strength compared to their LDPE counterparts. PET waste plastics, being the most commonly available in the environment in Uganda, a consideration was made for them; basing on the strength requirements of ordinary paver blocks for domestic construction, adding PET in proportions up to 40% of the total plastics content would still keep the strength properties within the required ranges, giving up to 19.8N/mm2 and 2.56 mm2 compressive and flexural strength respectively. It was concluded that mixing both PET and LDPE plastics can be done using an optimum sand composition of 60% when using ordinary methods such as a masonry oven or a fire place. Also the achieved compressive and flexural strengths were acceptable for domestic purpose paver blocks.