Setting evaluation of cement mortar using nondestructive methods under different curing conditions: temperatures and relative humidities

In this study, the effects of the curing conditions on the setting of cement mortars are investigated using nondestructive methods, electrical resistivity and ultrasonic wave velocity. Nine curing cases with different temperatures and relative humidities were considered. The electrical resistivity and ultrasonic wave velocity were monitored for 24 h after mixing to evaluate the setting and hardening. In addition, mercury intrusion porosimetry was combined with X-ray diffraction analysis to explore the differences in the results between the two nondestructive methods. The obtained nondestructive parameters from the electrical resistivity and ultrasonic wave velocity measurements showed different trends according to the changed curing conditions. High relative humidity at constant temperature induced carbonation of calcium hydroxide more than at low relative humidity, resulting in pore refinement by the calcium carbonate precipitation. The carbonation during the curing process did not affect the solid-phase network in ultrasonic wave velocity, while the electrical resistivity was affected by the pore water due to the carbonation.

Automated summary

The effects of curing conditions on cement mortar setting were investigated using nondestructive methods, electrical resistivity and ultrasonic wave velocity. Nine curing cases with different temperatures and relative humidities were considered. The obtained nondestructive parameters showed different trends according to the changed curing conditions. High relative humidity at constant temperature induced carbonation of calcium hydroxide more than at low relative humidity, resulting in pore refinement by the calcium carbonate precipitation. The carbonation did not affect the solid-phase network in ultrasonic wave velocity, while it affected the electrical resistivity due to the pore water.