Evaluation of the Effect of Molasses on Compressive Strength and Water Absorption of Cement-Gold Mill Tailings-Sand Mixture

This study investigates the effect of molasses as a natural admixture on the compressive strength and water absorption of a cementitious mix incorporating gold mill tailings (GMT) and sand. A constant mix ratio of 30% cement, 40% GMT, and 30% sand by weight was used, with molasses incorporated at varying dosages (0%, 1.5%, 2.0%, and 2.5% by total solid mass). The resulting mortar samples were evaluated for compressive strength and water absorption at 7, 14, and 28 days of curing. The results showed that a 1.5% molasses dosage produced the highest 28-day compressive strength (15.83 MPa), representing a 101% increase over the control mix (7.87MPa). The 1.5% molasses dosage also achieved the lowest water absorption (7.2%), which was 19% lower than that of the control mix (8.9%). In contrast, higher molasses levels (2.5%) resulted in reduced performance, likely because excess sugar interfered with cement hydration. Analysis of variance revealed that molasses dosage and curing age had a statistically significant effect on compressive strength (p < 0.01), while no significant difference was found for water absorption. These findings highlight the potential of combining GMT and molasses to produce sustainable, low-cost cementitious materials for non-structural applications, such as masonry blocks. The use of molasses not only improves performance but also offers a viable alternative to synthetic admixtures, supporting circular economy and waste valorization goals. Further research is warranted to evaluate long-term durability and environmental safety for practical applications.