Epoxy injection for masonry crack repair

Abstract

Masonry and concrete structures often exhibit cracks due to impact and dynamic loading, static overload or creep. Minor cracks can be tolerated depending on the exposure conditions but major cracks are aesthetically unpleasant and affect the durability of the structure. Recently, there has been an increasing use of epoxy resins in the repair and rehabilitation of concrete structures. But epoxy injection is less common in stone repair. The cracking that occurs in historic masonry can be static, progressively widening, or widening and narrowing in a cyclical fashion. Prior to carrying out any crack repair, the cause should be ascertained and if of the first two types, remedied. Although some stone structures have been repaired by epoxy injection during the last decade, test data available are too limited to conclude that the repaired stone structure is as strong as the original one. So the aim of this dissertation was to see whether this technique can be successfully used on our local building limestone, that is whether the original strength of a cracked stone is regained after being injected with epoxy resin. Four, locally readily available epoxy-resin systems, adequate for injecting, were selected for testing. They were tested as received without additional filler. These were tested on both oven-dry stone, and also on saturated surface dry stone. The tests performed were flexural strength test and the shear strength test. The intention of these experiments was to compare the original beams and samples to the repaired ones, with respect to mode of cracking and ultimate flexural and shear strength.