Abrasion deterioration of multi-generation recycled concrete with plastic waste under sulfate exposure

The simultaneous exposure to mechanical abrasive wear and aggressive chemical attack poses a severe threat to the service life of sustainable concrete infrastructure. This study investigates the abrasion deterioration kinetics of multi-generation recycled concrete incorporating plastic waste inclusions under continuous 5 wt% magnesium sulfate (MgSO4) exposure for up to 280 days. Six concrete mixtures were evaluated: first-generation recycled concrete (Mix A) and its plastic-modified variants (Mix A10 and A20), second-generation recycled concrete (Mix B) and its plastic-modified variant (Mix B10), and third-generation recycled concrete incorporating plastic waste (Mix C). Abrasion deterioration were evaluated using a multi-parameter degradation framework integrating surface abrasion depth (D i ), the Abrasion Deterioration Index (ADI), slope-based interval wear rates (W r ), and SEM-EDS microstructural mapping. Results demonstrate a distinct bi-phasic deterioration behavior: during early exposure (28–84 days), recycled mixtures exhibited accelerated surface scaling, with Mix A20 reaching a peak wear rate of 0.79 × 10 −2 mm/day due to porous adhered mortar and pre-existing microcracks. Conversely, plastic inclusions (Mix B10) provided an energy-absorbing buffer that retarded early ion diffusion. At ultimate exposure (280 days), third-generation recycled concrete (Mix C) experienced the highest structural degradation (ADI>1, mass loss of 0.13%). SEM observations revealed microstructural damage, while EDS elemental distributions showed compositional variations consistent with possible sulfate-induced alteration. This study establishes the quantitative link between multi-generational recycling loops and surface wear kinetics, offering practical guidelines for designing durable, plastic-buffered recycled concrete in harsh chemical environments.