Effects of sodium carbonate on self-healing properties of cement–slag–limestone powder ternary cementitious material

Abstract

Cement–slag–limestone ternary cementitious materials are cement-based materials with significant potential for applications, it exhibits extremely low carbon emissions and excellent workability. Now, to lower CO2 emissions of concrete industry the use of ternary blends is gradually popularized, and the investigation of their self-healing properties of it is of interest to the construction industry. So far, the effect of sodium carbonate on the self-healing of cement-slag-limestone ternary cementitious materials is not clear. In this study, we prepared ternary blends with different concentrations of sodium carbonate (0 %, 2.5 %, and 5 %) were prepared. And systematically investigated the self-healing ability of the samples through a combined macro-microscopic experimental method. Macroscopic aspects: The compressive strength of the samples was tested after 28 days of curing, and the changes in the crack width and relative permeability coefficients were recorded during the self-healing period. Microscopic aspects: The samples were examined for calcium and sodium ion leaching using an inductively coupled plasma optical emission spectrometer. The crack interiors were observed using a scanning electron microscope. And the healing compounds were tested using X-ray diffraction and attenuated total reflection Fourier transform infrared spectroscopy. The result shows, sodium carbonate reduced the 28-day compressive strength of the slurries and the number of leached calcium ions. The addition of 2.5 % sodium carbonate promoted the early permeability resistance repair of the ternary cement, and the addition of 5 % sodium carbonate reduced the self-healing ability of the ternary cement.