STABILITY OF FRIEDEL-SALT IN CARBONATED CONCRETE STRUCTURAL ELEMENTS

It is of significant scientific and engineering benefit from the corro sion view point, to know the state of Friedel's salt in concrete struc tures subjected to the simultaneous attack of chlorides and atmospheri c carbonation. An attempt is made in the present experimental investig ation to elucidate the role of atmospheric carbonation on the stabilit y of the Friedels salt in chloride contaminated structures. For this p urpose, four different types of concrete slabs, were subjected to chlo ride penetration over a total period of about three years and then exp osed to atmospheric carbonation for almost the same period. The stabil ity of Friedel's salt, based on XRD and DTA results is shown to be pH dependant. The solubility of Friedel's salt increases with the degree of carbonation of the concrete. It is also concluded that the stabilit y of ettringite is also pH dependant.