Prediction of Durability of Concrete in Monuments using Fracture Mechanics / Vorhersage der Dauerhaftigkeit von Beton in Baudenkmalen durch Anwendung der Bruchmechanik

The extension of cracks and pores are considered to be a theoretical basis for the prediction of durability of concrete of monuments. For this purpose a two-level structural model has been introduced: (I) matrix of hardened cement paste with fine and coarse aggregates, (2) voids and cracks created by external actions. The main parameter of this approach is the critical stress intensity factor: [xxx] The stress intensity factor of the material in the vicinity of the crack tip governs the crack growth. If all micro- and macro-defects are taken into consideration on the different levels of the hierarchic structural system, it is possible to formulate the global response. Each pore or crack creates a characteristic stress field around its­ elf in the material. If these pores are classified into periodic volume elements, the individual stress fields can be superimposed. This results in the complex state of stress under an imposed deformation.