The main aim of this research is to study the effects of adding polyethylene terephthalate or ‘PET’ waste to high-performance concrete (HPC) and the resulting properties and behaviour under freezing–thawing conditions. Natural sand is substituted with the PET aggregates at varying dosages (0–7·5% by volume of the sand) to produce HPC mixes. Mechanical properties of HPC were evaluated. The freezing–thawing resistance was measured to determine the durability factor (DF) of HPC with and without PET aggregates. The results indicated that the frost resistance of concrete mixes containing various amounts of PET aggregate was better than that of the reference mix, and the higher DF was that of the mix containing 5% replacement ratio, during 300 cycles of rapid freezing and thawing tests. The use of PET waste aggregates presented various advantages like increased flexural strength, improved frost resistance and a change in failure mode. This research study ensured that recycled waste plastic as a substitution of sand in HPC can help with decreasing the consumption of natural sand and with solving some of the environmental problems posed by plastic wastes.