Renovation | "Horchgänge" Petersberg Citadel Erfurt

Vibrant yet uniform surfaces

After the repair of the natural stone masonry in the "listening passages", visitors can not only simply enjoy the federal horticulture show BUGA; they can go on a journey to another world, to a time long gone. The maxit mur 950 HS used is equipped with a highly sulphate-resistant cement as a binding agent, so that reactions with joint areas contaminated with gypsum are excluded. With a maximum grain size of 4 mm, the grout also ensures a lively and at the same time homogeneous structure of the joint surface.

Joint renovation as in the Middle Ages

The Petersberg Citadel, built in the 17th century, is to blossom anew as part of the BUGA (federal horticulture show) Erfurt 2021. Against this background, the company Denkmalplan from Körner was commissioned to repair the secret "listening passages" of the citadel. The use of very clayey lime mortar during construction, as well as different procedures for maintaining the joint areas, had caused numerous break-outs in the joint areas over the years. The natural stone masonry of the "listening passages" showed extensive damage; gaps and depressions, in some cases over 40 mm, ran through the joints. In addition, the narrow and over 2,000-metre-long corridors offered little space and required work without the practical aids of our time.

Jointing by hand

The joints were first thoroughly freed from loose and friable joint material and prepared in such a way that the grout to be placed reached an average thickness of at least 2 cm. Missing areas were filled with stone and mortar. For the grouting itself, maxit mur 950 HS grout was used, which had previously been adapted to the existing natural stone in terms of colour and mechanical-physical properties. Due to the confined space, the material had to be carried through the corridors and processed there by hand (jointing iron, wooden board), as in earlier centuries.

Denkmalplan – Gesellschaft für Bauwerksanierung mbH

  • maxit mur 950 HS, coloured

Project location