Reduce Cement Content in Concrete by Enhancing Mechanical Properties with Chi-tin Nanofibers 

Reduce Cement Content in Concrete by Enhancing Mechanical Properties with Chi-tin Nanofibers and Nanocrystals
Presented By: Somayeh Nassiri, University of California Davis
Chitin is the second most abundant biopolymer after cellulose and is found in many species, including crustaceans. The nanofiber structure of chitin in shrimp shell waste was extracted in this study by mechanical and chemical methods, producing chitin nanofibers (ChNF) and nanocrystals (ChNC), respectively. Their surface functional group, size, morphology, and zeta potential were characterized. Testing of a range of dosages in mortar showed that ChNF (0.05%wt) with a larger aspect ratio than ChNC resulted in the greatest improved flexural strength and fracture energy by 24% and 28 percent. In addition, elastic modulus increased by up to 91% and 43% with ChNC and ChNF. With their anionic surface charges, both chitin nanomaterials induced electrostatic interactions with cement particles and caused a delay in setting time and increased the viscosity of the fresh cement slurry. Findings so far indicate chitin is a viable biomass source for powerful structural nanofibers to strengthen cementitious materials and reduce cement demand in concrete.