Highly Deformable Polymers for Repair and Strengthening of Cracked Masonry Structures

Abstract

Damages existing in masonry engineering
structures are caused by various loads and has to be repair
because of structural and architectural requirements. Repair of
cracked masonries using materials of high stiffness and low
deformability, like lime and cement mortars or epoxy resins, does
not increase significantly the tensile strength of the repair joint.
This is because of the stress concentration occurrence. The use of
highly deformable bonding materials allows reducing peaks of
stress concentration, causing (after repair) increase of strength of
cracked masonry elements. Proposed repair materials of high
deformability can be easily covered with original masonry
material to ensure protection of architectural value.
In the paper, there were tested masonry units (bricks),
investigated in two kinds of loading. One of them was the four
point bending test on Polish Bonarka bricks and the second one
was the Single Lap Shear Test on Italian Rosso Vivo - A6R55W
bricks, strengthened using CFRP and SRP strips bonded on
epoxy resin. In both cases, the primary failure appeared in form
of cracks (or detachment) going through the brick materials. The
failure surfaces of both tests were repaired using materials of low
and high deformability. More significant strength increase of the
tested masonry elements (after repair) was obtained in the case
of the use of highly deformable interface materials than of barely
deformable bonding materials.
Efficiency of highly deformable repair materials was also
examined as repair on cracked masonry walls in laboratory using
polymer injection and externally bonded composite mats made of
glass fibers bonded on highly deformable polymer. Additionally,
the highly deformable polymer joints were tested dynamically in
situ on a masonry building, up to failure also.