Effect of temperature rising inhibitor on autogenous shrinkage of cement pastes

Abstract

This study examines autogenous shrinkage behavior of cement pastes affected by temperature rising inhibitor (TRI). Dynamic elastic modulus, hydration kinetics, mineral phase compositions, pore solution and microstructure development were investigated by ultrasonic method, isothermal calorimetry, quantitative X-ray diffraction, inductively coupled plasma-optical spectroscopy and electrical resistivity, respectively. The results of the investigation indicate that reduction in surface tension of the pore solution is not due to the impact of TRI. Conversely, it is shown that growth process of ettringite crystals in pore solution the inhibition is delayed which results from the decreased growth rate of ettringite in pore solution and the slow dissolution rate of aluminum from clinkers affected by TRI. This is used to explain the derivation trend of mineral phases of clinkers, chemical compositions of pore solution, and decreases in the autogenous shrinkage of cement pastes. Experiments involving TRI and pure calcium sulfate aluminum clinker indicate expansion stress generation for a longer period when compared to that in the cement pastes only containing TRI, thereby confirming delayed ettringite growth mechanism.