Influence of curing temperature on the hydration and strength development of Class G Portland cement

A broad experimental program has been performed to characterize the hydration and strength development of a Class G oil well cement under various curing temperatures from 15 to 87 degrees C. The progress of hydration was monitored by isothermal calorimetry, thermo-gravimetric analysis, and quantitative X-ray diffraction based on Rietveld refinement; while the strength development was evaluated by both nondestructive ultrasonic tests and destructive crush tests. Test results indicate that heat of hydration, non-evaporable water content and degree of hydration of the cement follow approximately linear relationships, which are largely independent of curing temperature; the obtained proportionality constants agree well with those estimated by previously proposed empirical equations. The influences of curing temperature on the hydration rate and strength development rate can be modeled by an equivalent age method coupled with the Arrhenius law. The apparent activation energy obtained from hydration analysis was higher than that obtained from strength development analysis.

Automated summary

The experimental program investigated the hydration and strength development of Class G oil well cement under various curing temperatures. Results showed linear relationships between heat of hydration, non-evaporable water content, and degree of hydration, largely independent of curing temperature. Curing temperature influences hydration and strength development rates, which can be modeled using an equivalent age method.