Concrete damage in underground structures

Abstract

In this paper we present an overview about our findings concerning the damage o f under ground concrete structures. Case studies were performed in Austrian highway and railroad tunnels and associated structures for drainage and ventilation. In several cases severe damage o f the concrete was found owing to sulphate attack, alkali aggregate reactions, leaching and drainage clogging. The focus of this study is to demonstrate by some selected examples how to decipher the causes and reaction mecha nisms o f damaging reactions. Thus besides conventional mineralogical and hydro-geochemical methods we apply stable isotope and trace element signals within multi proxy approaches. For instance stable iso tope results indicate that SO 4 2and CO 3 2 " from local ground water are mostly responsible for thaumasite formation. More detailed knowledge on individual reactions responsible for concrete damage in under ground structures will help to find specific counter measures for already affected buildings and to develop proper concrete recipes, applications and constructive measures for future projects.