ABSTRACT
This study has been developed in three phases: the first one concerns samples collected in structures submitted to relatively stable temperature and variable degrees of relative humidity; the second one refers to structures located in a hot climate region with a high relative humidity; and the third phase, now in progress, consists of the carrying out of analyses of concrete submitted to cold and very humid conditions. The concrete of the structures analysed in the three phases was deteriorated by the microorganisms themselves or by their metabolisms. The research has been developed using techniques indicated for microstructural studies. This paper shows some images of deteriorated crystals and strange morphologies. The mineralogical calculation detected cement missing in some of the concrete samples. A comparison of the studies of the three phases is made and finally some conclusions are presented.
