Evaluation of concrete patch repairs
Experiments were carried out to study: a) the parameters which influence the efficiency and quality of remote robotic hydroerosion for removing defective concrete, b) the flexural behaviour of 6 different types of generic repair materials, c) the water permeability of the above 6 types of generic repair materials, and d) the parameters which influence the adhesive strength of patch repairs. In order to evaluate the efficiency and quality of remote robotic hydroerosion, 4 sets of parameters (concrete, pressure, generating unit, demolishing unit and nozzle parameters) were investigated using 7 series of tests. The flexural behaviour of 6 different types of generic repair materials was investigated by performing 160 flexural tests on solid, unrepaired and repaired beam specimens. The water permeability of the above 6 different types of repair materials was investigated by using ISAT and absorption by immersion tests on 100x100x100 mm cubes. Finally, 4 parameters (type of substrate surface, strength of substrate, type of repair material and use of bonding/agent primer), which influence the mode of failure and value of the adhesive strength of patch repairs were investigated by performing 300 pull-off tests. In the experimental study, fringe-based laser interferometry was used to measure and characterise the roughness of concrete substrates prior to repair. Results obtained using the above method proved the ability of remote robotic hydroerosion to produce surfaces with higher roughness values which in turn promote the adhesive strength between concrete substrates and repair materials.