Cellulose Nanocomposites for Performance Enhancement of Ordinary Portland Cement-Based Materials

Abstract

Cellulose nanofibril (CNF) with a high aspect ratio, elastic modulus, tensile strength, and reactive surface area is a promising nanomaterial for improving the chemo-mechanical properties of cementitious matrixes. CNFs are typically less than 0.2 mm in length and 50 nm in width, and are extracted from plants and trees. This study investigated the potential application of three types of CNF for enhancing the performance of ordinary Portland cement (OPC) pastes: pure CNF (PCNF), silica coated CNF (SCNF), and lignin-containing CNF (LCNF). The performance of the cement pastes was monitored for cement paste workability, hydration kinetics, microstructural development, and mechanical performance (compressive strength and flexural strength). The dispersion stability of CNFs measured through zeta potential showed a better dispersion for SCNF when compared with PCNF and LCNF in varied alkaline mediums. The better stability of SCNF also resulted in improved workability of the cement paste mixtures containing this type of cellulose. All of the cellulose nanomaterials accelerated the cement hydration at the early stage as a result of the nucleation effect. Such an acceleration effect was slightly higher for SCNF because of the presence of silica nanoparticles. The addition of 0.1% SCNF increased the compressive strength (90 days) by 13% when compared with the control batch and 10% compared with the PCNF batch. The addition of 0.1% of PCNF enhanced the flexural strength by 70% followed by LCNF with 40% improvement. SCNF showed little to no effect on the flexural strength.