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

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.