Recycled plastic aggregate can be used as an alternative material to produce lightweight concrete with low environmental impact. Polypropylene is one of the least recycled post-consumer plastics. In the present study we focused at waste expanded polypropylene (EPP) aggregate that is used for partial replacement of natural aggregate to produce lightweight cementbased composites. Coagulated silica was used as admixture for improvement of dispersion of EPP particles in the cementbased matrix. At

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... rst, natural and EPP aggregates were examined. Coagulated silica was characterized by SEM, EDS, XRF, particles size distribution and pozzolanic activity. Analysis of the microstructure of lightweight concrete was performed using an optical microscope, SEM imaging and EDS. For the developed lightweight concrete, basic physical, mechanical and hygric properties were examined. Specific attention was paid to thermal properties. The results show, using of plastic waste aggregate led to a sufficient mechanical resistance, whereas the thermal insulation performance of the developed concrete was markedly improved. Composite with incorporated PP waste aggregates was found to be prospective material for nonstructural applications in building industry, which allows the development of buildings with optimum energy performance as well as reduce the growing environmental impact of waste polymers and saving the natural aggregates.