Current projects (Applied Geology)

Development of a qualification programme regarding the construction material and the usage of hot lime mortar for environmentally damaged masonry of historical buildings

© Thomas Köberle

© Thomas Köberle

The immediate processing of dry-slaked lime mortar after the addition of water and sand on the construction site is a historical technique, which gained increasing attention in the recent years. Mortar processed this way - so-called hot lime mortar - is empirically attributed with a large porosity, high early strength and adhesion.

© Thomas Köberle

Due to its tendency for low shrinkage and fast stiffening also thicker mortar layers can be applied without shrinkage cracks. The craftsmen describe a slight expansion during the hardening which leads to a good adhesion and a force-fitting bond in the joint area. However, besides some occasional applications in the repair work there is a leakage of scientific-based knowledge on the hardening process and special features of the mortar.

The listed characteristics of the mortar are predestined for the repair work of environmentally damaged, salt loaded and flood damaged historical masonry.

© Thomas Köberle

The project aims for two goals: the bundling and transfer of practical experiences and knowledge on the processing technique of hot lime mortar by means of workshops on the one hand, and on the other hand the analysis of samples in order to quantify the empirically described characteristics regarding compressive strength, porosity, fabric, water absorption and salt-storing-capacity.

In addition, plastering works which were operated in the described technique shall be evaluated according to their long-time behaviour.

Duration:

• April 2017 until March 2019

Researcher:

Cooperation:

• Hochschule für Bildende Künste Dresden, Fachklasse für Kunsttechnologie, Konservierung und Restaurierung von Wandmalerei und Architekturfarbigkeit (HfBK); Prof. Dr. T. Danzl

• Institut für Diagnostik und Konservierung an Denkmalen in Sachsen und Sachsen-Anhalt e.V. (IDK); Dipl.-Min. M. Zötzl

• Dipl.-Rest. T. Schmidt, freiberuflicher Restaurator, Leisnig

• Restaurator im Maurerhandwerk Alexander Fenzke, DenkMal Fachbetrieb für Restaurierung und Altbausanierung, Bad Marienberg

Funding:

• Deutsche Bundesstiftung Umwelt (DBU) Aktenzeichen: 33877/01-45