Effect of cellulose nanofibers on the rheological and mechanical properties of cement pastes with metakaolin and natural volcanic pozzolan

Abstract

This study investigates the influence of cellulose nanofibers (CNF) on the rheological and mechanical properties of Portland cement pastes with pozzolanic additions, focusing on compressive ductility. Unlike prior research that examines individual factors, this comprehensive analysis evaluates various parameters affecting CNF-enhanced pastes. Using commercially available CNF and two pozzolanic additions—metakaolin (MK) and natural volcanic pozzolan (NVP)—the study assesses mechanical and ultrasonic methods for CNF dispersion. CNF is added at 0%, 0.05%, and 0.5% by weight of cement (CEM). Results show distinct differences in flow curves and thixotropy, both with and without ultrasound. Compressive strength tests at 28 days reveal that 0.05% CNF is optimal for CEM ＋ MK pastes without ultrasound, outperforming Portland cement pastes with NVP. However, 0.5% CNF significantly improves compressive ductility in CEM and CEM + NVP pastes, despite reduced compressive strength. This study offers valuable insights into optimizing mechanical properties of CNF-modified pastes, enhancing the efficacy and sustainability of construction materials.