Deep Creek Bridge was built in 1981 and is in the coastal area of the Northern NSW and subject to tidal salt water. The bridge has shown signs of premature deterioration in the form of vertical cracking which varies in severity in the pier columns. Based on visual observations, it was suspected that alkali-aggregate reaction (AAR) and corrosion of reinforcement could be the two major probable causes of the cracking. AAR is considered to be the major cause of the observed cracking, and reduction in the strength properties of the concrete. The large pier columns may have been subjected to temperature rises to or beyond 80oC, as a result of cement hydration, causing delayed ettringite formation. However, this would probably have had a minor contribution to the observed cracking. Chloride-induced corrosion has also been identified, and may have been exacerbated by the AAR microcracking. The pier columns may require cathodic protection (CP) to arrest the progress of steel corrosion and damage to the structure. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E208431.
Samenvatting