Non destructive and medium destructive analyses on an early 20th century reinforced concrete structure: the case study of the Victory Monument in Bolzano

The analytical results highlighted clear differences on the materials’ properties between the concretes of the walls and the vaulted slab and the concretes of the stairway structural elements. The concretes of the walls and the vaulted slab are plain and they are generally characterized by low compressive strength values and wrong mix designs, rich in sand fraction and poor in cement. A direct relation between cement content and compressive strength has been found. As regards the concrete of the lateral walls, an improvement in concrete quality was observed in the sections far from the ground: this characteristic is compatible with a gravitational segregation of the fresh conglomerate during the constructive phases. All these characteristics suggest a structural conception of these elements to withstand compressive stresses only. The concretes of the beams and stairway slab are reinforced and show better characteristics, with high compression strength values, better mix designs and higher cement content. These evidences indicate a more accurate structural plan for the realization of these elements, in order to optimize their flexural behavior. Finally, a diffuse degradation of the elements was observed, due to carbonatation of the cement matrices, alkali-aggregate reactions, sulphate attack and soluble salts crystallization events. All these alteration dynamics are due to the extreme environmental conditions of the basement, characterized by significant variations in relative humidity and temperature values.