Sustainable use of alternative water sources for concreting: Strength and technoeconomic perspectives

Water quality prominently influences the mechanical performance and cost-effectiveness of concrete, a critical factor in sustainable construction. This study evaluates the effects of water quality sourced from tap water, rainwater, groundwater, and secondary treated wastewater on the workability, compressive strength, and economic viability of M20 grade concrete. Water samples were chemically characterized to ensure compliance with relevant standards before use in casting and curing concrete. Compressive strength tests conducted at 7 and 28 days showed that concrete mixed and cured with groundwater achieved strengths of 16.43 MPa and 22.13 MPa, respectively, while concrete prepared using secondary treated wastewater reached 16.17 MPa at 7 days and 23.00 MPa at 28 days, both comparable to the tap-water as control (17.45 MPa at 7 days and 24.93 MPa at 28 days); in contrast, rainwater-based concrete exhibited consistently lower strength development, around 67% of the control’s strength at 28 days. Techno-economic analysis revealed that although concrete mixed and cured with tap water achieved the highest compressive strength, it incurred the highest cost per unit strength ($0.69/MPa). In contrast, treated wastewater ($0.10/MPa) and groundwater ($0.39/MPa) provided more cost-effective alternatives, demonstrating improved economic efficiency without significant compromise in performance. Statistical analysis confirmed no significant strength differences at 7 days, but significant variations at 28 days, emphasizing the delayed impact of water quality. These findings support the sustainable use of alternative water sources in concrete production, balancing durability and cost efficiency. • Concrete strength was evaluated using water from different sources (tap, rain, groundwater, and treated wastewater). • Water quality had no impact at 7 days but significant effects at 28 days. • Groundwater and treated wastewater produced strength comparable to tap water. • Rainwater based concrete showed low strength and slower development over 28 days. • Techno-economic analysis revealed that treated wastewater is the most cost-effective alternative.