Direct tensile strength of lightweight concrete using polypropylene coarse aggregate coated with sand

Plastic waste used as coarse aggregates in structural concrete is part of efforts to minimize environmental pollution. It can provide lightweight concrete but with a lower strength compared to normal concrete. Accordingly, an experimental study of 12 concrete specimens using waste polypropylene coarse aggregates coated with sand was carried out. Direct tensile tests were conducted to cylinder concrete specimens having diameter of 10 cm and depth of 20 cm respectively. Three mixtures of sand coated polypropylene coarse plastic aggregate, river sand as fine aggregate, water and Portland Composite Cement with a water-cement ratio of 0.286 were conducted. The mass proportion of cement and sand are the same but the mass of plastic coarse aggregates coated with sand is specific for each mixture. Direct tensile strength of the specimens in general shows that higher tensile strength is found for specimens having higher compressive strength. From the test results, a model of direct tensile stress-strain relation is proposed. Finally the direct tensile strength for lightweight concrete using polypropylene coarse aggregate coated with sand is found to be lower than the direct tensile strength for normal concrete.