Cellulose nanofibrils in pervious concrete: improving mechanical properties and durability

Pervious concrete (PC), commonly used in urban pavement, is known for its high permeability, which contributes to mitigating the urban heat island effect. However, the low strength and durability of PC limit its use. The objective of this study is to improve mechanical properties and durability of PC by adding cellulose nanofibrils (CNFs). The results showed that CNFs significantly enhanced compressive strength, flexural strength, and salt frost resistance, with optimal performance at 0.15% CNF. At this concentration, compressive and flexural strengths increased by 26.5% and 25.8%, respectively, despite a slight reduction of 10.2% in permeability. CNFs also improved resistance to salt-induced freeze–thaw cycles, reducing spalling and maintaining a higher value of the dynamic modulus of elasticity, particularly at 0.1% and 0.15% dosages. Scanning electron microscope (SEM) analyses revealed that CNFs create a denser, more uniform network of hydrated products, enhancing microstructure and interfacial bonding. This study confirms that CNFs can significantly enhance the mechanical properties and durability of PC.