EFFECT OF DOMESTIC WASTEWATER ON THE WORKABILITY AND COMPRESSIVE STRENGTH OF CONCRETE.

ABSTRACT The growing demand for water in construction has led to the exploration of alternative water sources for concrete production. This study investigates the feasibility of using laundry wastewater (LWW) as a substitute for potable water (PW) in concrete mixing and curing. The research examined the effects of LWW on concrete properties, including workability, density, and compressive strength. The study aims to determine whether LWW can serve as a sustainable alternative to PW without significantly compromising concrete performance. A series of laboratory tests were conducted, including sieve analysis, specific gravity, moisture content, slump test, and compressive strength testing at different curing ages (7, 14, and 28 days). The slump test revealed that LWW-cast concrete had lower workability (30 mm slump) than PW-cast concrete (50 mm slump), indicating that LWW reduces fluidity due to the presence of residual detergents and impurities. Density results showed slight variations, with LWW-cast concrete ranging from 2485.93 kg/m³ to 2502.22 kg/m³, compared to PW-cast concrete, which ranged from 2450.37 kg/m³ to 2562.93 kg/m³. The compressive strength of LWW-cast concrete was consistently lower than PW-cast concrete, with a 28-day strength of 17.34 N/mm² compared to 20.00 N/mm² for PW-cast concrete. These results suggest that LWW negatively affects concrete strength, likely due to impurities that interfere with cement hydration. Despite its limitations, LWW presents a potential sustainable alternative for non-structural concrete applications, such as pavement blocks and non-load-bearing walls. To improve its suitability, it is recommended that LWW undergoes pre-treatment to remove impurities before being used in concrete production. Additionally, the use of chemical admixtures, such as superplasticizers, could enhance the workability of LWW-based concrete. Quality control measures should be implemented to ensure consistency, and further studies should focus on optimizing LWW treatment processes and long-term durability assessments. In conclusion, while LWW offers environmental and economic benefits by reducing freshwater consumption in concrete production, its impact on workability and strength necessitates careful evaluation before widespread adoption in structural applications.