Effect of temperature rising inhibitor on expansion behavior of cement paste containing expansive agent

Abstract

The present study aims to examine the mechanism influencing the expansion characteristics of expansive cement paste in presence of different dosages of Temperature Rising Inhibitor (TRI). The expansion of cement pastes showed a higher expansion strain of the OPC-EA mixture with 0.2% and 0.4% TRI in comparison to the reference sample and a decreased shrinkage of cement pastes containing expansive agent (OPC-EA). Meanwhile, dynamic elastic modulus, hydration kinetics, mineral phase compositions and microstructure characterization of hydration products were also investigated by ultrasonic method, isothermal calorimetry, quantitative X-ray diffraction and scanning electron microscope, respectively. The delayed hydration process of expansive agent increases the amount of expansive agent available to react after the setting of cement pastes, resulting in the increased expansion strain of OPC-EA-0.2%TRI sample. The higher expansion strain of OPC-EA-0.4%TRI sample can be attributed to the lower stiffness of cement paste affected by TRI. The results showed that the addition of TRI is the main force in delaying the hydration process of ye’elimite in expansive agent by acting on the formation and morphology of ettringite. The delayed ye’elimite hydration process can be explained by inhibition of the precipitation or/and growth of ettringite.