Former Professor of Industrial Engineering and Management Science, Eindhoven University of Technology

This paper discusses how to arrange durability testing in such a way that the results constitute a proper basis for an unequivocal judgement of the capacity of masonry to avoid deterioration with time. The complexity of deterioration is reduced by modelling based on a transition process. For every transition from a given performance state to a lower grade state the principles of fracture mechanics with respect to cyclic stress ratios are applied. This is a direct link to accelerated testing by means of a cyclic generation of fortified stress ratios. The holding times in every state follow from the transition probabilities. Most likely, the transition process generates a Weibull hazard rate. This is the basis of the required probabilistic model to represent test data and to interpret the results in probabilistic, terms and associated parameters. Some relevant cases are described as examples of destructive deterioration. It appeared that testing of walleltes is not only easier than testing of single parts of a masonry system, but more appropriate. For parts and their assembly on the building site, the emphasis is on technology, including process and quality control.