Evaluation of saturation and microcracking of the superficial zone of concrete: new developments

Proper surface preparation is essential for the durability of the repaired structure as well as specific saturation level of the concrete. Moreover, the repair material is often blamed for “not sticking”, but the general source of the trouble lies with the substrate surface conditioning. The extensive research project has been undertaken to develop specifications and performance criteria for surface preparation of concrete substrates, one of the tasks of which was to develop a field test to evaluate the optimum moisture conditioning of the substrate concrete prior to application of repair material. The Autocalm system has been calibrated and compared with destructive and non destructive tests (Schmidt hammer, microscope observations and water absorption) on three types of concrete and two types of surface preparation. In order to evaluate different saturation levels, concrete samples have been stored in more than 12 modes of conservation.