Mortars with enhanced chemical resistance: Effects of sulphuric acid exposure

In this work, a comparative study on the mechanical, microstructural and chemical properties of mortars with enhanced chemical resistance was performed to investigate the effects of sulphuric acid attack. For this, specimens of ordinary and improved formulations were immersed in water and sulphuric acid at pH 0.0 for 14 days, assessing the relative residual compressive strength and corrosion depth. The sulphuric acid attack resulted in pronounced changes in the mechanical properties and severe corrosion for the ordinary mortar. In contrast, the improved mortars exhibited moderate to high acid resistance (relative residual strengths up to 94.6% and minimal corrosion depth of 0.5 mm). A significant quality gain of up to 49% and 180% was also observed when comparing the improved mortars with a reference mortar resistant to acid in terms of relative residual compressive strength and corrosion depth, respectively. The effect of sulphuric acid attack on the microstructure and chemical composition of mortars was further evaluated by mercury intrusion porosimetry (MIP), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy with energy dispersive X-ray (SEM-EDX).