Study on the early cement hydration process in the presence of cationic asphalt emulsion

Abstract

Cement-asphalt (CA) paste could be regarded as the Portland cement (PC) paste with enhanced flexibility due to the addition of asphalt emulsion (AE) and could be utilized as the semi-flexible pavement and repairing materials. In order to extensively explore the process of early cement hydration and the microstructure evolution of PC paste in the presence of cationic AE, various measurements including setting time, hydration heat, conductivity, compressive strength and ultrasonic pulse velocity, Fourier transform infrared spectroscopy (FTIR), chemically bound water, thermogravimetric (TG) and field emission scanning electron microscopy (FESEM) were adopted in the investigation. The experiment results showed that the setting process of PC paste was gradually prolonged with the increase of A/C, implying that the formation of microstructure of PC paste was inhibited by cationic AE, which is in agreement with the hydration heat and conductivity test. The compressive strength and pulse velocity of ultrasonic wave of cement mortar reduced with the incorporation of cationic AE, which thus implied the porosity increases with the addition of A/C, and in turn indicating the generation of microstructure of cement paste was suppressed gradually with the increase of cationic AE, this could also be confirmed by the chemically bound water, FTIR and FESEM results. Finally, the possible retardation mechanism of cement hydration, caused by the cationic AE, was proposed.