Thesis (B.S.) -- Cagayan State University, 2025.

This study explores the feasibility of using Peñablanca limestone powder (PLP) as a partial substitute for Portland cement in concrete, with a focus on workability, mechanical performance, and cost-effectiveness. In response to the urgent need to reduce carbon emissions in the construction sector and to promote the use of locally available materials, the research employed a true experimental design using four concrete mix variations containing 0%, 10%, 15%, and 20% PLP by weight of cement. The concrete specimens underwent slump testing to evaluate workability and were tested for compressive and flexural strength at 7, 21, and 28 days of curing. One-way ANOVA and Bonferroni post hoc tests were used to analyze statistical significance among the different mix designs. Results showed that the incorporation of PLP improved workability, attributed to its fine particle size enhancing internal mix lubrication. Compressive strength remained comparable to the control mix at 10% and 15% PLP, while a decline was observed at 20% replacement. Flexural strength was more sensitive, with significant variations observed across all replacement levels and curing ages. Cost analysis highlighted a reduction in material expenses, with the 20% PLP mix being the most economical at P226 compared to P282 for the control, largely due to decreased cement usage and the availability of locally sourced limestone at no cost. The study concludes that Peñablanca limestone powder is a viable, sustainable alternative for partial cement replacement, particularly at 10% to 15% substitution, offering environmental and economic advantages without compromising structural performance.

Keywords: Peñablanca limestone, cement replacement, sustainable construction, concrete mix, compressive strength, flexural strength, workability, environmental impact.