▎ 摘　　要

NOVELTY - Cement composite comprises Portland cement; and graphene nanoplatelets or helical carbon nanotubes. It is free of chemical dispersing aids. The cement composite has a fracture toughness of at least 0.65 MPa(square root of m). The cement composite has a porosity of no greater than 8.5%; and the cement composite has a water absorption of no greater than 4.5%. USE - The cement composite is useful as essential ingredient in concrete. ADVANTAGE - The composites have high concentrations of graphene nanoplatelets or helical carbon nanotubes that do not require chemical dispersion aids or dispersion-enhancing chemical surface functionalization.