The TSA degradation process of cement-based materials in the electrical field environment

The thaumasite form of sulfate attack (TSA) of cement-based materials is a complex degradation process. However, there is no detailed study on the TSA degradation process in an electrical field environment. XRay Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy (Raman) and chemical analyses were used to study the TSA degradation process based on the present studies. The results indicated that the degradation process of the electrical field cathode Na2SO4 solution-anode MgSO4 solution group was similar to the Na2SO4 and MgSO4 solution full immersion, with the main difference being the degradation rate. The electrical field can obviously accelerate the TSA degradation process. The degradation had progressed to the centre of the sample, and the amount of pulp was found in the electrical field group at 120 days. The degree of degradation of the MgSO4 full immersion affected only the surface of the sample at 360 days. The degree of degradation of the MgSO4 full immersion was the lowest at 360 days. Meanwhile, combining the XRD, chemical analysis data and appearance, the degradation rule was summarized as there being a fixed range to generate the pulp (the representative thaumasite form of sulfate attack), and the pH and the Ca/S need to meet the following conditions: 10.6 < pH < 11.8 and 4.0 < Ca/S < 6.4. (C) 2019 Elsevier Ltd. All rights reserved.