Bio-functionalization of metakaolin for better performance of metakaolin mortars

This study was conducted to investigate the influence of gallic acid (GA), the smallest molecular unit of tannic acid, on the performance of metakaolin (MK) mortars. GA was added directly as an admixture (Method I) or pre-mixed with MK (Method II) for bio-functionalization. Experimental results showed that GA improved the dispersion of MK by generating electrostatic repulsion and spatial site resistance between particles. The GA functionalization of MK by Method II displayed superior efficiencies in adjusting the fluidity of mortars owing to better dispersibility. The functionalization of MK by GA could enhance the pore filling effect resulting from the dispersed MK, and enable more products to be generated owing to the formation of GA similar to Ca intermediates, contributing refined pore structure and increased compressive strength to mortars. The compressive strength of MK mortars has been optimally increased by 13.0 - 18.0% when using 0.1% GA.