Assessing the Use of Treated Wastewater for Pavement Quality Concrete and Dry Lean Concrete Layers in Rigid Pavements: Future-Proofing Infrastructure

Water plays a significant role in the production of concrete used in the construction of rigid pavements. Several countries are currently encountering stupendous water demand due to road infrastructure development. To reduce potable water usage and balance the water demand, an alternate approach is to use treated wastewater, specifically in the construction of pavement quality concrete (PQC) and dry lean concrete (DLC) layer presented in the rigid pavement. The current study explored the feasibility of using municipal and industrial treated wastewater at secondary and tertiary treatment levels in concrete production. Varied mineral aggregate sources were used and assessed for the suitability of treated wastewater for fresh concrete properties, mechanical properties, and durability. Microstructural analysis was conducted using scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) to gain a deeper understanding of the concrete composition. Test findings revealed that industrial-treated wastewater with higher dissolved and suspended solids showed a higher slump difference than tap water (TW) mixes. The compressive strength and split tensile strength difference between TW and treated wastewater samples were within 0%–10% at 28 and 90 days of curing. Microstructural analysis indicated uniformly formed ettringite in treated wastewater samples, contributing to higher early strength. Further, an inconsistency in the elemental composition of treated wastewater was observed when compared to TW. Marginal compressive strength and mass loss were identified when exposed to H2SO4. The study shows that reusing treated wastewater in PQC and DLC layers can significantly impact urban water management by saving enough water to meet the daily needs of over 5,000 people.