This thesis proposes a method for the non-destructive assessment of the strength of naturally aged glass, in order to reuse it. The method consists of the detection and characterization of the surface defects and the estimation of the failure stress, based on fracture mechanics. The novelty of the method lies on the equipment used, Traceit®, which is a mobile optical profilometer that allows the examination of Sglass in non-laboratory conditions. Non-destructive and destructive tests were conducted on 50+ year old glass to measure the strength of old glass and to assess the feasibility and accuracy of the method. Experiments on new glass were performed and used as a benchmark. The size effect on weathered glass was examined as well.

An approximate reduction of 50% in the strength of old glass was observed, compared to new glass. Furthermore, the size effect had no influence on the old glass, due to the uniform damage found on its surface. This implies that a lower threshold for the strength of old glass can be determined. Finally, with the proposed methodology, the critical defect was successfully detected in 23% of the specimens and a good estimation of the average failure stress was obtained.