ABSTRACT
Abstract Investigations into the structure and chemical composition of the cement paste-aggregate interfacial layers before and after the action of sulfate solution resp. sulfuric acid were carried out on sandwich-like specimens, consist ing of a flat polished aggregate substrate and a cement paste layer. They confirmed that transport processes and subsequent chemical reactions take place in a narrow, highly porous layer below the substrate covering textured portlandite film containing CSH-gel domains. Early investigations on samples from real concretes reveal that contiguous seems of sulfate containing compounds around the aggregate grains are not to be registered. Neverthe less there are obviously weak areas where penetrating ions accumulate. A novel interesting technique for the non destructive examination of the interface between cement paste and aggregate is IR-spectroscopy utilizing multiple attenuated total reflectance. Keywords: Cement Paste-Aggregate Interfacial Layers, Sulfate Attack, Sulfuric Acid Attack, IR-Spectroscopy
1 Introduction
The deterioration of concrete structures by aggressive media is to a large extent governed by transport processes in the pore space of the cement paste. It is well known that the paste-aggregate interfacial layers of normal concrete constitute a weak zone of lower mechanical strength and higher permeability. Yet, little is known about the influence of the cement paste-aggregate inter facial layers on concrete corrosion. A thorough under standing of concrete deteriorating processes, however, requires research into the connection between chemical reactions and transport processes in these layers. The following contribution, though it is far from comprehen sive, is an attempt to present some interesting aspects with respect to this discussion.
