A Study on the Comparative Environmental Impact Assessment of Recycled PET Permeable Blocks and Cement Permeable Blocks

In this study, we developed an environmental assessment method to investigate permeable blocks prepared using recycled polyethylene terephthalate (PET) as a binder. First, Los Angeles abrasion test was conducted to simulate the surface abrasion caused by the long-term use of water-permeable block, and the number of rotations was 100-300. To separate the microplastics from the residual fragments of the degraded surface of the permeable block, the microplastics were subjected to a flotation process using calcium chloride as a sorting solvent. The obtained microplastics from the abrasion test was quantitatively and qualitatively analyzed using a particle size analyzer, microscopy, and Fourier transform-infrared spectroscopy. To obtain the extract, the permeable block was subjected to a leaching test, and the pH and Ca concentration were measured. The pH of the cement-based permeable block (10.79 ± 0.17) was higher than that of the PET-based permeable block (9.58 ± 0.23). In addition, the extracts of recycled PET- and cement-based permeable blocks were subjected to an acute toxicity test using Daphnia, and the results revealed that the toxic unit of the recycled PET permeable blocks was 0, whereas that of the cement-based permeable blocks was 1.98 ± 0.11.