Comparison of corrosion resistance mechanism between ordinary Portland concrete and alkali-activated concrete subjected to biogenic sulfuric acid attack

The difference of corrosion resistance mechanism between alkali-activated concrete (MC) and ordinary Portland cement concrete (OPC) under biogenic sulfuric acid corrosion was compared. By measuring the local surface morphology, mass loss, compressive strength and Ca2+ dissolution of OPC and MC specimens, the corrosion resistance of these two kinds of concrete to biogenic sulfuric acid (BSA) was studied. The hydration products and corrosion products of OPC and MC were studied with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and environmental scanning electron microscopy-energy dispersive spectroscopy (ESEM-EDS). The results show that under BSA corrosion, the thickness, roughness and porosity of the corrosion layer of OPC are obviously greater than those of MC. The main corrosion products of OPC and MC is gypsum. The amount of gypsum produced on the surface of OPC corrosion layer is larger than that of MC. In addition, the bacterial effect on the surface of MC corrosion layer is greater than that of OPC, which makes the corrosion path of BSA shorter than that of OPC. Therefore, the corrosion resistance of MC to BSA is better than that of OPC. (C) 2019 Elsevier Ltd. All rights reserved.