External sulfate attack in structural concrete made with Portland-limestone cement: an experimental study

This experimental study aims to assess the effect of external sulfate attack on structural concrete made with a common Portland-limestone cement. The experimental campaign, lasted about three years, has been performed on standard-sized cylinders (Φ15×30 cm) subject to different exposure conditions. The overall swelling of the specimens due to chemical reactions was monitored in time. SEM-EDS observations and XRD tests were also carried out. Results showed the presence of secondary ettringite causing swelling and micro-cracks formation. The porosity increase due to sulfate attack of the outer skin of the specimens was measured. Ultrasonic measurements and compression tests on cores drilled from the cylinders immersed in different solutions allowed to confirm and quantify the consequent degradation of macroscopic elastic properties.