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

Abstract

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 1.5% molasses dosage produced the highest 28-day compressive strength (15.83 MPa) and the lowest water absorption (7.2%), indicating improved matrix compaction and reduced porosity. In contrast, higher molasses levels (2.5%) resulted in reduced performance, likely due to excess sugar interfering with cement hydration. ANOVA results 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.