Abstract: Disclosed are composite materials comprising a porous, carbonated, calcium silicate ceramic having a microstructure comprising interconnected open pores; where the calcium silicate surface defining the pores is partially or completely coated with an amorphous silica layer, and the silica coating comprises an overlayer of calcium carbonate crystals; where the silica coating and calcium carbonate overlayer form a network that interconnects throughout the ceramic microstructure, but do not completely occlude the pores. Also disclosed are methods of forming such composite materials.