Role of biopolymers in enhancing multiscale characteristics of carbonation-cured cementitious composites

This study investigates the application of two natural biopolymers, i.e., polydopamine and nanocellulose, as performance-enhancing additives in carbonation-cured ordinary Portland cement (OPC) -slag blended com-posites. A multiscale investigation reveals that the addition of these biopolymers increases the formation of nanoporosity and reduces amounts of microporosity in the matrixes. Both biopolymers are also found to increase the degree of reaction in the binders. Incorporation of 0.05 wt% polydopamine increases the flexural strength of the composites by 55% after 28 days of curing. A similar flexural strength improvement (-66%) can also be achieved by adding nanocellulose. Moreover, the addition of these biopolymers increases the early age (-3 days) compressive strength of the carbonated composites by nearly 35%. It is postulated that the addition of poly -dopamine enhances performance by creating stronger bonds with the reaction products and by stabilizing amorphous CaCO3. On the other hand, the addition of nanocellulose improves the strength by bridging microcracks.