Fiber composite materials in historical masonry

Project data

Titel | Title Faserverbundwerkstoffe im historischen Mauerwerk  | Fiber composite materials in historical masonry Förderer| Funding Bundesinstitut für Bau-, Stadt- und Raumforschung (BBSR) im Bundesamt für Bauwesen und Raumordnung (BBR) Zeitraum | Period 12.2015 – 11.2018 Leiter | Project Manager Prof. Dr.-Ing. Wolfram Jäger (Professur für Tragwerksplanung) Bearbeiter | Contributor Dipl.-Ing. Fabian Meyer, Dipl.-Ing. Hassan Youssef

Report in the annual report 2018

FIBRE COMPOSITE REINFORCEMENT IN MASONRY

When preserving and strengthening historical constructions, bracing and anchoring of damaged or insufficiently self-supporting masonry are technologies that are frequently applied. The use of a steel bar to brace masonry has the disadvantage that a suitable cement-containing mortar is required to ensure corrosion protection. But there are compatibility problems associated with cement if the masonry contains sulphate. An expansive reaction occurs through the formation of ettringite.

A potential alternative here is fibre-reinforced plastics. The intention of the research project is to research the key principles of fibre composite reinforcement used for the purpose of bracing and anchoring historical masonry and to examine building materials and technologies used in practice. This will help establish conditions that will enhance the quality of building materials’ use in monument preservation when renovating historical masonry. The solutions must be sustainable and must be able to satis-
fy the increased demands being made in the area of monument preservation. Regarding the theoretical foundations, the professor for the structural design of the faculty of architecture performed extensive experimental analyses on the behaviour of composites. For the analyses, test bodies made of natural sandstone, varying grouting mortars and braces made of glass fibre reinforced plastics (GFRP) or carbon fibre reinforced plastics (CFRP) were produced. By performing structural pull-out tests, with large and small bonded lengths, it was possible to determine and analyse the bond stresses in the composite system.

Furthermore, the susceptibility to torsion of the fibre composite building materials and the pre-stress characteristics in the masonry were examined using technologies that are used in practice. The structural pull-out tests of the bars supplied important information on the behaviour of the composites in the composite components. It could be shown that conventional strengthening methods using a steel bar and cement as grouting mortar can be replaced by the use of fibre composite reinforcement and gypsum-containing grouting mortar in historical masonry containing sulphate.

For that reason, the experimental analyses of the behaviour of the composites represent an important contribution to the preservation and strengthening of historical constructions in ways suitable for monuments.