Durability and environmental evaluation of rice husk ash sustainable concrete containing carbon nanotubes

The environmental issues in the construction industry have garnered considerable attention in numerous studies. Ecologically sustainable green concrete addresses environmental challenges in the construction industry. This study investigates the impact of multi-walled carbon nanotubes (0-0.20%) in rice husk ash (15%) concrete to replace Portland cement. The mechanical and durability properties of four concrete mixtures were analysed. Adding 0.1% multi-walled carbon nanotubes and 15% rice husk ash yielded satisfactory results, significantly improving durability compared to concrete without multi-walled carbon nanotubes. With the addition of 0.1-0.2% multi-walled carbon nanotubes, the density and elastic modulus increased, the 28-d sorptivity decreased by 4.64-28.76%. The resistance ability of 111-d mass loss and compressive strength loss increased by 50.93-61.71% and 25.28-48.47% under sulphate attack, respectively. The resistance ability of mass loss increased by 3.7-35.97% under acid attack. And 120-d drying shrinkage resistance improved by 3.08-9.23%. The predicted and experimental results were compared using the Sakata, GL 2000, B3, ACI 209, and CEB-FIP models. Sakata and B3 provided the most accurate early-stage and long-term drying shrinkages with variation coefficients of 0.13-0.33 and 0-0.05, respectively. Moreover, the sustainability of rice husk ash concrete containing multi-walled carbon nanotubes was evaluated, and its environmental friendliness was confirmed. Thus, the viability of multi-walled carbon nanotubes in rice husk ash sustainable concrete significantly contributes to sustainable construction.