Eco-friendly cement mortar production using rice husk ash and oyster seashell powder: A comprehensive study of mechanical, durability and life cycle properties

Abstract

This study develops eco-friendly cement mortar by synergistically combining rice husk ash (RHA) and oyster calcinated seashell powder (OCSP), leveraging their complementary properties to enhance mechanical and durability performance and sustainability, offering a novel solution for sustainable construction. Mechanical properties, including compressive, splitting tensile, and flexural strength, were evaluated at 7 and 28 days of water curing. Durability was assessed through sodium sulphate resistance, chloride ion penetration, and freeze-thaw tests. The Life cycle assessment was performed using Simapro software by following European standards. Results revealed that mortar with 15 % RHA and 10 % OCSP exhibited approximately 20 % higher compressive, splitting tensile, and flexural strengths compared to the control sample, though strength properties declined at higher RHA and OCSP contents (20 % and 15 %, respectively). Porosity decreased slightly, with the R15S10 mixture showing the lowest porosity (9.7 %) compared to the control (10.2 %). Durability tests of control sample indicated a 20 % compressive strength loss under sodium sulphate exposure, while the 15 % RHA and 10 % OCSP mixture demonstrated five times greater resistance. The chloride ion diffusion coefficient decreased by about 50 % (from 8 ×10⁻¹² m²/s in the control), and freeze-thaw resistance improved significantly with RHA and OCSP incorporation. Life cycle assessment revealed that RHA and OCSP-based mortar had lower environmental impacts in acidification, eutrophication, climate change, photochemical ozone formation, and resource use. These findings highlight the potential of RHA and OCSP based mortar for urban green building construction, where enhanced durability and reduced environmental impact are critical.