Development and testing of cellulose nanocrystal-based concrete

Engineers are continuously looking to improve the performance of existing materials. Nanostructured cellulose (cellulose nanocrystals or nanocellulose) offers a high aspect ratio and mechanical strength that may support development of a new class of concrete adapted for extreme environmental conditions. In this study, we developed and tested various types of cellulose nanocrystal (CNC)-based concrete for application in the construction industry. Specifically, three CNC-based concrete specimens with different cellulose nanocrystal types and proportions were tested to understand the effects of nanocellulose on structural concrete performance. Destructive and nondestructive testing, along with surface morphology characterizations, were conducted to evaluate the performance of the CNC-based concrete specimens. The destructive and nondestructive tests yielded similar results. Higher CNC proportions improved the concrete's microstructure and produced higher ultrasonic pulse velocities along the same path length. Furthermore, results from Schmidt hammer rebound tests confirmed that the CNC-based concrete specimens with higher crystallinity, higher aspect ratios, and rougher surfaces were able to sustain larger loads with smaller crack developments. Finally, results from rapid chloride permeability tests indicated that the addition of 0.25 wt% cellulose nanocrystals in the CNC-1 concrete specimen and 0.75 wt% cellulose nanocrystals in the CNC-2 concrete specimen produced the highest peak resistance against water and chloride ion penetration. These findings can guide future research and development of this novel and innovative material.