Environmental Risk Assessment of Sustainable Concrete Through the Chemical Composition of Metals and Polycyclic Aromatic Hydrocarbons

The waste management sector is crucial for protecting the environment, conserving resources, and promoting sustainable development by ensuring efficient disposal, recycling, and minimizing the harmful impact of waste. This study aims to understand the performance levels (compressive strength), environmental impact, and overall sustainability of three concrete mixes, two of which use recycled materials. The mixes are defined as a conventional mix, mix one, which replaces dune sand for recycled rubber in the mix design, and mix two, which utilizes recycled aggregate as a replacement for fine aggregates. SEM-EDS is used to assess the elemental composition and surface morphology of the materials. The potential leaching of pollutants such as polycyclic aromatic hydrocarbons (PAHs), non-targeted organic compounds, and heavy metals was obtained using GC/MS and ICP-OES. The results showed low concentrations of PAHs in all mixes and a low calculated Potential Ecological Risk Index (PERI), where the conventional mix and mix two had the lowest risk (55 and 33, respectively) compared to mix one, which displayed a higher risk of 125. The results of the heavy metals assessment yielded that mix one was the most contaminated, with 1535 mg/kg of nickel and 1200 mg/kg of zinc, followed by the conventional mix, with 1385 mg/kg of nickel and 135.5 mg/kg of chromium, and finally, mix two was the least contaminated with 378.5 mg/kg of nickel and 142.5 mg/kg of zinc. Overall, the sustainability potential showed that mix two, with the recycled aggregates, was the most sustainable, with a Building Material Sustainability Potential (BMSP) value of 9.25. The study advocates for a shift toward sustainable concrete practices to mitigate environmental impacts while maintaining structural integrity.