Freeze-Thaw Durability of Anchor Materials in Heritage Masonry Stones

Repair of heritage stone masonry structures sometimes involve anchoring the walls, to prevent from separation and to increase integrity of the walls. Performance of these anchors significantly depends on their ability to resist debonding forces induced from environmental freeze-thaw. Before choosing any anchoring materials for a heritage structure repair, capability of these materials in forming a sound bond with the existing masonry materials of that structure needs to be examined. A study was conducted at the University of Manitoba in collaboration with the Public Works and Government Services Canada (PWGSC), to test the behaviour of several anchors in stones. Conventional anchoring materials consist of steel, grout, and epoxy. On the other hand, suitability of Glass Fibre Reinforced Polymers (GFRP) to overcome the corrosion related problems of steel is well established. Keeping this aspect in mind, innovative anchors made from GFRP bars were also incorporated in this research program. Experimental program involved small scale replication of stone-anchor assemblies followed by monitoring of these assemblies for failures, while they were exposed to environmental chamber freeze-thaw cycles, in the W.R. McQuade Structures laboratory of the University of Manitoba. Varying rate of change of temperature and level of relative humidity were maintained in the environmental chamber during these exposures. At the end, monitoring data were analyzed to draw conclusions.