Long-term durability evaluation of fiber-reinforced ECC using wood-based cellulose nanocrystals.

• CNCs have features that promote hydration of un-hydrated areas in cement. • Hydration products increased up to 18% compared to plain specimen without CNCs. • The results of the durability evaluation of the fiber-reinforced specimens to improve the CNC mixing ratio and ductility behavior showed significant strength improvement at the mixing ratio of 0.8 (vol%). • Excellent results even in long-term durability through the effect of reducing voids in cement due to increased hydration products. As part of the study for the development of sustainable construction new materials for fiber reinforced high-toughness cement composite (ECC) using wood-based cellulose nanocrystals (hereinafter referred to as CNCs), this study assessed the applicability of CNCs through epidemiological performance assessment and long-term durability assessment. CNCs were prepared in the form of suspensions after dispersion and replaced with mixing water. The mixing rate of CNCs was 0.4, 0.8, 1.2 vol% Compared to cement, and the fiber types were Flax and Steel fiber. First, the amount of hydration products produced by the addition of CNCs was up to about 7% higher than that of plain specimen, and the value of strength was up to 20% at 0.8 vol%. Of steel fiber reinforced. Therefore, to evaluate the long-term durability according to the optimum mixing ratio of CNCs 0.8 vol%, compressive strength after freezing and thawing, acceleration carbonation, and chloride ion penetration resistance test were conducted. In the case of freezing-thawing, the strength ratio was lower than that of plain specimen, but the strength value itself increased by about 20% after freezing thawing. In the carbonation promotion test, the carbonation depth was reduced by about 60% compared to plain specimen. In the case of chlorine ion penetration resistance, the fiber-reinforced test specimens showed high value due to voids in the adhesion surface with cement due to the use of chlorine ions, but the C08 test specimen showed a resistance value of 5% lower than plain specimen confirming the validity of CNCs. [ABSTRACT FROM AUTHOR]