A novel inherently hydrophobic and physicomechanically robust coconut oil-based polyurethane-modified mortar

Water penetration in mortar structures has long been a significant challenge in the construction industry, resulting in metal bar corrosion, structural deterioration, reduced durability, and increased maintenance costs. Hence, enhancing water resistance is crucial. While surface coatings are common solutions, they are often costly and require frequent maintenance. To address this concern, this study presents a novel coconut oil (CO)-based polyurethane (PU)-modified mortar, leveraging the intrinsic hydrophobic properties of CO owing to its saturated fatty acid structure. Different concentrations of COPU (0-7 wt.%) were investigated to determine the optimal formulation. The characterization results indicated enhanced hydrophobicity, with a water contact angle of 125° achieved at the 2 wt.% COPU addition to the PMM mixture, compared to 110° of the control sample. Additionally, the water absorption test demonstrated a significant 54 wt.% reduction compared with that of pristine mortar, attributed to the gap-filling and binding actions of the COPU matrix with ettringites, as evidenced by SEM analysis. This modification also resulted in a 40 wt.%, being the highest improvement in compressive strength (from 13.1 to 18.4 MPa at 2 wt.% COPU) and a slight reduction in density. Additionally, the prepared samples were evaluated using thermogravimetric analysis, X-ray diffraction, and X-ray fluorescence analyses. The findings in this work advance the field by presenting eco-friendly COPU-modified materials that improve water resistance and durability in mortar, promoting sustainable practices.