Preservation of historic buildings

Preservation of historic buildings


The protection, repair and preservation of historical building fabric as well as the assessment of the durability of different building materials are key research areas of ibac. The work in these areas is complemented by decades of experience in the field of building inspections and non-destructive testing techniques.

Natural stone

One of ibac's traditions since the 1970s has been research into building material issues in the restoration of natural stone and historic masonry.

Surveys of existing structures and damage are accompanied by material investigations specifically adapted to the respective project situation. Questions about the material composition of historical mortars, the qualitative and quantitative salt content are answered and mechanical and hygric material parameters are determined. A wide range of experience is available in the development and optimisation of grouting and backfilling mortars as well as stone supplements. In particular, the optical, hygric and mechanical properties are adapted to the historical building materials. One focus of the research area is the study of material behaviour as a function of dynamic weathering processes. The ibac is also involved in a wide range of monitoring programmes for durability testing during construction, mostly with non-destructive testing.

Another major research focus is the non-destructive determination of moisture depth profiles using nuclear magnetic resonance (single-sided NMR). With this method it is possible to determine the moisture content of a rock stratum in steps of up to 10 µm. Currently, the penetration behaviour of old hydrophobic coatings is being investigated using NMR.

Cooperation with other institutes at RWTH, for example the geological institute, enables interdisciplinary research.

Protection with textile concrete

Textile concrete is a high-performance material consisting of concrete or mortar and technical textiles (e.g. made of AR glass or carbon fibre), which are used instead of the usual steel reinforcement to absorb tensile forces. Its many advantages include low layer thicknesses (from 20 mm), low weight, high load-bearing capacity and corrosion resistance of the reinforcement.

The use of textile-reinforced protective layers is particularly interesting for the repair or reinforcement of listed concrete and reinforced concrete structures, where the appearance must not be changed but the measure must be sustainable. In addition to a low layer thickness, textile-reinforced concrete has the advantage that a large number of mineral rehabilitation variants are possible, thus ensuring the compatibility of the materials. By absorbing the deformations, a reduction of the service life can be ruled out.