PU from coconut oil polyols could inhibit water ingress in mortars

Mortar is an essential construction material but its intended service life can be shortened by water absorption. Researchers led by Jason Paraguya at Mindanao State University, Philippines, have investigated the use of a novel hydrophobic mortar containing polyurethane made with a coconut oil polyol. The research has been published in the academic journal Scientific Reports.

The study explores how adding small amounts of this coconut-oil-based polyurethane (COPU) to conventional mortar significantly boosts hydrophobicity and durability.

he team added varying proportions of COPU (0–7 wt %) to a standard cement–sand–water mix, and found that an addition of just 2 wt % produced the best balance of properties. At this level, the modified mortar achieved a water contact angle of roughly 125°, up from about 110° for the unmodified control, indicating much stronger water-repellent behaviour.

In the same formulation the water absorption after 24 hours of immersion dropped by approximately 54% compared with control samples, and compressive strength rose from around 13.1 MPa to 18.4 MPa at the 2 wt % COPU level – about a 40% improvement. Micro-structural studies (SEM) revealed that the COPU network filled voids around cement hydration products, while XRD showed that the typical crystalline hydration phases were disrupted by the polymer matrix.

The authors said the material offers several advantages: enhanced water resistance and durability, lighter density compared to standard mortar, and the use of a renewable bio-based feedstock (coconut oil) instead of petroleum-derived polymers. They see potential applications in wet or marine environments, infrastructure exposed to moisture, and lightweight construction for high-rise or seismic-resilient structures. The researchers note that further work is required on long-term durability, scale-up and economic viability.

Photo by Tijana Drndarski on Unsplash

Scientific Reports