A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Calcium sulfate is the common set regulator in Portland cement. It is shown that ground clinker can be set regulated by other soluble calcium salts than gypsum. Rheology of paste is improved when gypsum is replaced by the other salts, due to less hydration and less crystals of acicular shape. For in particular calcium nitrate the cumulative hydration energy is reduced under isothermal conditions, which opens up for low-energy cement without changing clinker chemistry. The effect is confirmed by temperature profiles of mortar curing under semi-adiabatic conditions. Substituting calcium sulfate may also allow heat curing, or allow temperature in massive structures to exceed 70 °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 °C for 3 days. Linear expansion vs. time is steadily increasing for mortar with gypsum, while mortar with calcium nitrate is dimensionally stable.
Calcium sulfate is the common set regulator in Portland cement. It is shown that ground clinker can be set regulated by other soluble calcium salts than gypsum. Rheology of paste is improved when gypsum is replaced by the other salts, due to less hydration and less crystals of acicular shape. For in particular calcium nitrate the cumulative hydration energy is reduced under isothermal conditions, which opens up for low-energy cement without changing clinker chemistry. The effect is confirmed by temperature profiles of mortar curing under semi-adiabatic conditions. Substituting calcium sulfate may also allow heat curing, or allow temperature in massive structures to exceed 70 °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 °C for 3 days. Linear expansion vs. time is steadily increasing for mortar with gypsum, while mortar with calcium nitrate is dimensionally stable.
Properties of gypsum-free Portland cement
Justnes, H. (author)
Journal of Sustainable Cement-Based Materials ; 3 ; 128-139
2014-04-03
12 pages
Article (Journal)
Electronic Resource
English
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