Activation energy of calcium sulfoaluminate cement-based materials

In this study, calcium sulfoaluminate (CSA) cement pastes were tested for heat of hydration and chemical shrinkage at temperatures of 20 degrees C, 30 degrees C and 40 degrees C. Apparent activation energy (Ea) values were then calculated using both exponential and hyperbolic methods. The average Ea of the CSA cements ranged from 42.24 to 80.22 kJ/mol, much higher than that of Type I Portland cement (3845 kJ/mol). Ea increased slightly with the replacement of silica fume for cement. However, average Ea decreased by 18.4% when 20% Class C fly ash was used, but increased by 21.3% when 40% Class C fly ash was used. Ea calculated from heat of hydration using the exponential method is 17% lower than that obtained using the hyperbolic method. When the exponential method was used, Ea values determined using heat of hydration were 30% higher than those obtained using chemical shrinkage.

Automated summary

This study found that the average Ea values of CSA cements are high, with slight increases when silica fume replaces cement, and potential decreases or increases when Class C fly ash is used. Ea values calculated using different methods may vary, with those determined using heat of hydration being higher than those obtained using chemical shrinkage when using the exponential method.