Equations for Predicting Flexural Strength and Compressive Strength of Plastic Concrete Pavement Blocks

The influence of plastic content within the range of 0% - 60% as replacement for sand volume, water cement (w/c) ratio of 0.30 – 0.50 and curing age of 7 days – 28 days on flexural strength and compressive strength of plastic concrete pavement blocks (PCPBs) was investigated. All the mixtures were proportioned with a fixed aggregate / cement ratio of 4.5. Based on the experimental results, the flexural strength and the compressive strength of the PCPBs were calculated by considering the predictor variables (water cement ratio, curing age and plastic content). Equations derived based on the results from the experimental work are proposed to predict the flexural strength and the compressive strength of the developed PCPBs. The effect of water cement ratio, curing age and plastic content on flexural strength and compressive strength of PCPBs was found to be statistically significant (P < 0.0001). The equations are only capable of predicting the flexural strength and the compressive strength of plastic concrete products, if the w/c ratio, the curing age and the aggregate cement ratio used are within the tested range. Keywords: water cement ratio, plastics, curing age, flexural strength, compressive strength.

Utilization of Waste Low Density Polyethylene in High Strengths Concrete Pavement Blocks Production

The disposal of waste plastics is causing a great challenge in Ghana and the world as a whole as the usage of plastics is growing day by day and it takes centuries for waste plastics to decompose. Hence, there is the need to adopt effective methods to utilize these plastics.  The main objective of this research was to investigate the feasibility of using waste low density polyethylene as partial replacement for sand in the production of concrete pavement blocks. In this study cement, sand, coarse aggregate, and ground plastic were used. The mix proportion was 1: 1.5: 3 (cement: sand: coarse aggregate). The plastic was used to replace the sand by volume at 0%, 10%, 20%, 30%, 40%, 50%, and 60%. It was observed that density, compressive strength, flexural strength, and splitting tensile strength decreased as the plastic content increased. However, the water absorption increased as the plastic content increased. Compressive strengths level ranging from 14.70N/mm2 – 47.29N/mm2 were achieved when water cement ratios of 0.30 – 0.45 were used. Although, the strengths of the pavement blocks decreased as the plastic content increased, compressive strengths of 20N/mm2, 30N/mm2, and 40N/mm2 which are satisfactory for pedestrians walk ways, light traffic and heavy traffic situations respectively could be achieved if 10% - 50% plastic contents are used. It is concluded that the modified pavement blocks would contribute to the disposal of plastics in the world. Keywords: plastic concrete pavement blocks, water cement ratio, compressive strength, curing age