Compressive strengths of Portland cement, slag and gypsum mixtures

Compressive strengths of concretes containing Portland cement (10 to 100%), slag (0 to 90%) and gypsum (0 to 40%) at different periods were determined. Results show that cements having good strength can be made from mixtures containing 10% Portland cement, 20% gypsum and 70%} slag. Mixtures containing clinker and gypsum in higher proportions also give good strength at later ages. Mixtures containing both clinker and gypsum in high proportions but slag in low proportion show unsoundness.