The sulfate degradation of cement incorporating carbonate by an electrical field at low temperature

Abstract

Sulfate and carbonate can cause serious degradation of cement-based materials at low temperature; degradation products generally include ettringite, gypsum and thaumasite. The degradation process is very slow in a natural environment and no useful test method exists to accelerate the degradation process. This study used a voltage of 30 V and an electrical field duration of 20 s to study the acceleration effect of an electrical field on the degradation. Visual observations and compressive strength were used to reflect the degree of degradation. X-ray diffraction, Fourier transform infrared spectroscopy and ion concentration distribution were applied to study the degradation mechanism. The test results indicated that an electrical field can accelerate the degradation within 180 d and that the degradation rate was faster than that associated with full immersion. Moreover, the degree of degradation of a solution with sodium sulfate (Na2SO4) as the cathode and magnesium sulfate (MgSO4) as the anode was higher than that of a solution with magnesium sulfate as both cathode and anode; also the degradation degree of a magnesium sulfate solution under full immersion was higher than that of a sodium sulfate solution under full immersion.