Experimental Study of the Effect of Nano-silica on the Mechanical Properties of Concrete/PET Composites

In this study, the mechanical properties of concrete composites containing waste PET (polyethylene terephthalate) and nano-silica were investigated to produce the lighter, more flexible and high-strength concrete. For this purpose, the different content of nano-silica was added to concrete containing 10 wt.% of waste PET aggregates. The mechanical properties and the morphology of the samples were investigated. The mechanical properties such as flexural, tensile and compressive strength of the composites declined with the PET aggregates, but the mechanical properties were significantly improved by incorporating the nano-silica. Optimum composition containing 10 wt.% of PET and 3 wt.% of nano silica was obtained, in which the tensile strength, compressive strength, and flexural strength were increased 27%, 30%, and 9% respectively compared to the neat concrete. The density of the optimum sample was decreased by 4% relative to the neat concrete. SEM (scanning electron microscope) images showed that introducing the nano-silica into concrete improved the interfacial transition zone between cement and the PET aggregates.