Properties of Gypsum-free Portland Cement

Ground Portland clinker can be set regulated by other soluble calcium salts than gypsum. Calcium nitrate reduced max temperature under semi-adiabatic conditions opening up for low-energy cement without changing clinker chemistry. Substituting calcium sulphate may also allow heat curing, or allow temperature in massive structures to exceed 70 degrees C, without risking delayed ettringite formation. Mortar based on clinker with 3.5 % gypsum and 2.0% calcium nitrate, respectively, was heat cured at 80 degrees C for 3 days and stored for 20 degrees C thereafter. Linear expansion vs. time is steadily increasing for mortar with gypsum, while mortar with calcium nitrate is dimensional stable during 2 years water storage.