Portland cement is not easily replaceable in its main use (building construction) because concrete made with organic substances as sand grain binders, be it cor

Portland cement is not easily replaceable in its main use (building construction) because concrete made with organic substances as sand grain binders, be it cornstarch or epoxy-polymer, isn't fire resistant. The compressive strength of cornstarch concrete maxes out at 26 MPa according to the paper, while different Portland cement formulations range from 20-50 MPa, and epoxy-polymer can go up to > 100 MPa, though brittleness is a problem. The optimal strategy for cleaning up Portland cement production is probably (1) renewable-based electrification of the kilns used to make CaO from CaCO3 (limestone), and (2) capture and stabilization of the CO2 from the kilns in a form like carbon fiber or diamond. Still a bit sci-fi but technologically feasible (but not economical at present).