Effects of carbonaceous particles and heavy metals on mortar-SO2 reactions

Abstract

The effects of carbonaceous particles and heavy metals in the interaction between sulfur dioxide and mortars were investigated in a laboratory exposure system. Simulation experiments were carried out in a flow chamber where temperature, relative humidity and SO2 concentration were controlled. Samples of lime, pozzolan and cement mortars were exposed for 150 days in air with 3 ppm of SO2 concentration at 25°C and 95% RH. The mortar specimens were coated with three types of carbonaceous particles, collected at the emission points of three oil-fueled combustion sources, and, for comparison, with particles of active carbon, pure graphite, iron oxide and vanadium oxide. After exposure, the mortar samples were analyzed by x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to identify the main chemical species, by ion chromatography (IC) to quantify SO 4 −− and SO 3 −− concentration and also by scanning electron microscope (SEM). The results show that the amount of SO 4 −− forming increases in the presence of carbonaceous particles and is related to their heavy metal content.