Influence of Polar Amino Acids on the Carbonation of Lime Mortars

The addition of protein-based additives (e.g. milk, egg white, animal blood) into lime mortars can improve mortar properties such as workability, strengths and durability. With the intent to understand how and why proteinaceous additives improve lime mortar properties, it could be useful to start from the basic building blocks of proteins amino acids. Consequently, the present study focuses on the influence of polar amino acids on the carbonation of lime mortars, and the results demonstrated that addition of amino acids into mortars could slow down mortar drying, increase surface hardness, slow down carbonation, promote amorphous calcium carbonate stabilization and inhibit calcite formation; moreover, these effects seemed to become more evident with the increase of amino acid concentration. It was speculated that in highly alkaline lime mortars, polar amino acids could lime carbonation by interacting with calcium carbonate via H-bonds and additional Ca2+ mediated adsorption.