Optimized ultrasonic attenuation measures for internal sulphate attack monitoring in Portland cement mortars

Sulphate attack is considered one of the most aggressive causes of concrete degradation. Ettringite triggers expansion mechanisms that have harmful effects on the Portland cement matrix, causing micro-cracking and, consequently, a reduction in the stiffness and strength of concrete. Portland cement composites are very dispersive and heterogeneous materials that makes very challenging to do non-invasive inspections to know the intrinsic properties and integrity of such material. In this work, the degradation process due to internal sulphate attack in mortar specimens has been monitored by means of an intensive broadband frequency analysis of ultrasonic attenuation and it has been compared with mechanical and expansion analysis, and the traditional ultrasonic pulse velocity (UPV).