An experimental study on mortar plaster incorporating banana leaf ash as partial replacement for cement and coconut Shell as partial replacement for fine aggregates for sufficient compressive strength and enhanced water resistance in Baguio city

Abstract

This study investigated the use of Banana Leaf Ash (BLA) and Coconut Shell (CS) as sustainable partial replacements for cement and fine aggregates in Type N mortar plaster. Performance was evaluated through compressive strength testing (ASTM C109) and water absorption analysis (ASTM C1403) at curing intervals of 7, 14, and 28 days. Experimental results revealed that combined replacement levels of 5%, 10%, and 15% failed to meet the mandatory 5.2 MPa required strength. While individual BLA replacements at 5% and 10% yielded strengths of 12.3114 MPa and 11.2416 MPa, and 5% CS achieved 6.9838 MPa, the compositional compatibility between materials proved incompatible at higher concentrations. To refine the mix, exponential regression and a 0.84 safety factor identified an ideal 3% combined replacement. This refined mix achieved a 28-day strength of 8.9168 MPa and a low 28-day water absorption rate of 2.66%. In contrast, the 15% replacement resulted in total early-stage failure with 0 MPa at 7 and 14 days and a significant 28-day water absorption of 5.80%. The study concludes that while increasing coconut shell content significantly compromises compressive strength and moisture resistance due to its porous and fibrous nature, BLA functions effectively with a pozzolanic property that facilitates secondary hydration reactions. When maintained at the 3% ideal replacement level, the mixture achieves the necessary structural requirements for Type N mortar. These results validate a sustainable framework for utilizing locally sourced agricultural by-products in high-altitude, high-rainfall environments, offering an eco-friendly alternative for housing construction in the Baguio City region.