Experimental evaluation of superplasticizer and recycled aggregates in high-performance coconut fiber-reinforced concrete

Abstract To address the limitations of conventional concrete, such as low ductility and toughness, high-performance fiber-reinforced concrete (HPFRC) incorporates fibers into a cementitious matrix. However, traditional HPFRC production using natural aggregates and industrial fibers depletes resources and increases environmental impact. This study explores a sustainable alternative by developing high-performance coconut fiber-reinforced concrete with 35% and 70% coarse recycled aggregates (RA) as partial replacements for natural aggregates, combined with 0%, 1.5% and 3% coconut fibers (CFs) by binder volume. The addition of 0.6% polycarboxylate ether-based superplasticizer significantly enhanced mechanical and durability properties. Compressive strength increased by 14.3%, splitting tensile strength by 19.2% and shear strength by 41.4%. Durability against freeze–thaw cycles and acid attacks improved, with an 18.6% increase in residual compressive strength and 18.5% enhancement in acid resistance. While CFs and RA initially increased water absorption and chloride ion permeability, superplasticizers mitigated these effects, improving overall durability. The synergistic use of CFs and superplasticizers enhanced resistance to environmental degradation, enabling RA to perform effectively under harsh conditions. This approach demonstrates the potential of integrating recycled aggregates and waste coconut fibers to produce eco-friendly, high-performance concrete for modern construction. The study highlights the balance between mechanical performance, durability and sustainability, offering a cost-effective solution that reduces the carbon footprint and promotes circular economy principles in construction.