Enhancing the properties of carbonation cured gamma dicalcium silicates (-C₂S) using biomimetic molecules

This study investigates the effectiveness of three different organic molecules to enhance the properties of carbonated gamma dicalcium silicate (gamma-C2S) based cementitious system. These molecules are addressed as biomimetic molecules due to their ability to mimic the biomineralization process. Low dosages (2.5% and 5%) of L-aspartic acid (LAsp), L-glutamic acid (LGlu) and polyacrylic acid (PAA) were incorporated to the gamma-C2S paste. The effects of these molecules on the microstructure, CO2 sequestration capacity and strengths of the CO2-activated gamma-C2S pastes were monitored. To understand the effectiveness of molecules at different temperature, the compressive and flexural strengths of gamma-C2S pastes carbonated at 25 degrees C and 50 degrees C were evaluated. It was observed that all the molecules enhanced the strength of the composites by altering the CaCO3 formation and subsequent densification of the matrix. However, the effectiveness of the molecules varies depending on the temperature. Specifically, LGlu and LAsp were found to be the most and the least, respectively, effective molecule at high temperature (50 degrees C) carbonation curing condition; whereas, PAA remained nearly equally effective at both temperatures.