Trass-lime reinforced mortars in strengthening and reconstruction of historical masonry walls: Fid-Bau Portal

Trass-lime reinforced mortars in strengthening and reconstruction of historical masonry walls

Jasieńko, Jerzy / Logoń, Dominik / Misztal, Witold

Highlights • Paper describes possibilities for limiting first cracking, strengthening and deflection in relatively weak trass-lime mortars used in the reconstruction of historical buildings. • The influence of mortar reinforcement on strengthening, repair and reconstruction of historical stone walls depends mainly on good anchoring (‘matrix-reinforcement’ adhesion). • Most effective when assessing first cracking was reinforcement which had the best anchoring, largest strength and highest Young modulus value. • The best results in terms of strengthening were achieved with hybrid reinforcement using highly-flexible carbon netting and low-flexible polypropylene fibres. • It appears that continuation of the research programme should address application of fibres, which are non-linear, and spatially distributed.

Abstract The paper describes the behaviour of tensile joints in irregular external faces of stone walls and the results of laboratory testing of selected technologies for strengthening mortar, which can be applied in strengthening, repair and renovation of historical stone masonry walls, with special references to structures with irregular faces. A research programme of the Building Institute at Wrocław Technical University on the effectiveness of strengthening irregular, three-leaf stone masonry walls using modern technologies is also presented. Special attention is devoted to technologies introducing stainless steel tie-rods Ø2mm in diameter into joints in the external wall face in conjunction with filling joints with trass-based mortar (TUBAG TWM). Results of laboratory testing of plates (40×160×138mm) of mortar reinforced with various types of synthetic fibres. Tests were carried out based on a four-point bending, which was treated as representative from the point of view the static behaviour of the reinforced tensile joints in the wall. The possibilities of curtailing the first cracking, strengthening and deflection of the trass-lime mortars are also described, in situations where the stress value exceeds that at which first cracks appear (FSD – first crack, strengthening, deflection). Composites were strengthened with dispersed polymer fibres, steel tie-rods, polypropylene and carbon netting. The analysis indicates that there is a need to identify a hybrid form of reinforcement as an effective solution for strengthening mortars in historical buildings, including joints in historical stone walls.