*Constituents that are permitted in Portland-composite cements are...
wikipedia - 13 Jan 2021*Constituents that are permitted in Portland-composite cements are artificial pozzolans (blastfurnace slag (in fact a latent hydraulic binder), silica fume, and fly ashes), or natural pozzolans (siliceous or siliceous aluminous materials such as volcanic ash glasses, calcined clays and shale).