Bond behaviour of light and heavy carbon fibre TRM to masonry interfaces

We present the results of an experimental campaign on the bond behaviour between carbon fibre textile reinforced mortars and masonry substrate. The campaign involved 54 single lap direct shear tests on masonry wallettes reinforced with a single TRM layer. The key investigated parameters were the type of the textile fibre material (light carbon and heavy carbon), the coating of the textile reinforcement with epoxy resin, and the bond length (100, 150, 200, and 250 mm). The results highlight the beneficial effect of the epoxy resin coating that practically doubles the maximum attained loads. This increase is shown to be associated to a consistent shift of the failure mode from textile slippage to detachment at the matrix to matrix interface. In the uncoated specimens, the maximum load is practically identical for heavy and light carbon. Conversely, in the coated specimens the maximum load attained by the heavy carbon fibre textiles is 65% higher than that of the light carbon coated fibre textiles. However, both coated textiles demonstrate the same exploitation ratio. Cost-wise, this renders light carbon an appealing choice in practical applications. The experimental observations are further examined in view of analytical modelling.