Service life prediction of concrete under freeze-thaw deicing salt attack with intermittent dry periods

Freeze-thaw cycles (FTC) with deicing salt solutions can lead to internal damage and external scaling of concrete. Depending on the concrete composition, a progressive, linear or degressive course of scaling occurs. Numerous models exist for the prediction of the scaling rate. However, there is still need for research to take intermittent dry periods (IDPs) into account, as they often occur in field practice during long summer months, but also in winter during days without precipitation. This contribution shows the effect of IDPs on outer and inner damage. Concrete with a w/c ratio of 0.45 was cast, cured and exposed to different cycles of freeze-thaw deicing salt attack with and without IDPs of different lengths. Water movement in the near surface concrete was observed using single-sided ¹H-NMR while the transport of chlorides was examined using chemical analysis of drilling dust as well as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). IDPs led to a significant reduction of the scaling rate and prevented inner damage. Different approaches to implement this knowledge into service life prediction are discussed.