In the Trois-Rivières area (Québec, Canada), several hundred foundations of private houses, apartment and public buildings were built using concrete incorporating an anorthositic gabbro coarse aggregate containing sulfide minerals. A large number of those concrete structures developed serious deterioration within 3 to 5 years after their construction, which triggered, in many cases, their demolition/replacement. To help understanding the deterioration mechanisms and the conditions most prone to the development of premature damage, as well as quantifying the rate of deterioration, concrete blocks, 1 m x 1 m x 0.225 mm in size, were extracted from housing foundations just prior to their demolition. The blocks were disposed on an outdoor exposure site where they were monitored for the development of cracking and expansion over a five-year period. More than three hundred cores were extracted at different depths in eight housing foundations. A variety of tests including in-situ relative humidity measurements, petrographic, physical, mechanical and chemical tests on those cores were conducted for a full condition assessment of the concrete. A good correlation was observed between the monitoring of crack and the development of expansion in concrete foundation walls of different initial damage degree. Deterioration was also found to be largely influenced by the exposure conditions and RH conditions within the concrete. The determination of the total sulfur content of the concrete is a way to estimate the amount of sulfide minerals in the aggregate but significant variability was observed on values measured on different core samples from the same foundation
