Sustainable high-performance geopolymer concrete incorporating nano clay and rice husk ash

Abstract

The growing emphasis on sustainable construction has accelerated research into eco-efficient high-performance concrete. This study evaluates the synergistic effects of nano clay (NC) and rice husk ash (RHA) as supplementary cementitious materials in high-performance geopolymer concrete (HPGC). Binder compositions were based on fly ash (FA), ground granulated blast furnace slag (GGBFS), or their blends, serving as primary aluminosilicate sources. Twenty-four formulations were prepared with RHA at 10–15 % and NC at 0–5 % by binder mass and compared with a Portland cement high-performance concrete (PC-HPC) reference. Tests covered fresh properties, mechanical performance, durability, and microstructure, with statistical correlation used to identify dominant parameters. NC significantly improved workability, increasing slump from 100 to 210 mm and apparent density from 2.30 to 2.44 t/m³ , enhancing cohesive and pumpable paste performance without compromising stability. The mix 225FA + 11RHA + 4NC + GGBFS achieved, at 28 days, compressive strength of 111.1 MPa, tensile strength of 8.9 MPa, flexural strength of 14.4 MPa, and modulus of elasticity of 44.12 GPa. It also exhibited excellent durability, with water permeability of 1.30 × 10⁻¹ ¹ cm/s, rapid chloride permeability of 229 coulombs, and sorptivity of 2.35 × 10⁻⁴ mm/s⁰.⁵). After 180 days in sulfate solution, compressive strength remained at 77.8 MPa, which was more than 20 MPa higher than PC-HPC. Microstructural analysis revealed a refined pore structure from NC’s high surface area and pozzolanic reactivity, while RHA contributed silica enrichment and valorized agricultural waste. Correlation analysis identified NC dosage as the primary factor influencing strength and durability, with FA–GGBFS blends further enhancing performance. These results highlight NC–RHA geopolymer blends as viable, eco-friendly alternatives to conventional high-performance concrete, promoting both environmental sustainability and structural longevity.