Nineteenth century hydraulic restoration mortars in the Saint Michael's Church (Leuven, Belgium) - Natural hydraulic lime or cement?

This research focuses on the characterization of nineteenth century hydraul ic restoration mortars used in the Saint Michael's Church in Leuven (Belgiu m). The mortars were used as restoration mortars for weathered mortar joint s. A historical study of old work descriptions and mineralogical, petrograp hical and chemical analyses have been used to characterize these hydraulic mortars. The different hydraulic phases are identified using petrographical analysis, X-ray diffraction analysis (XRD), scanning electron microscopy ( SEM) equipped with an energy dispersive X-ray spectrometer (EDX) and chemic al analyses. Based on the presence of gehlenite (C(2)AS), the dominance of C2S, the large amounts of portlandite, the chemical analyses and on the his torical sources, these hydraulic mortars are characterized as natural hydra ulic lime mortars. (C) 2001 Elsevier Science Ltd. All rights reserved.