In masonry materials, the effect of the soluble salts is one of the most common and important cause of weathering. They are involved in chemical attack, corrosion and mechanical stresses. In particular soluble salt can crystallize inside the porosity of the substrate (clay brick, concrete unit, grout, etc.) or between the discontinuity of the coupled materials (substrate-TRM). This process causes an increase in volume, which occurs during the water evaporation from the substrate with a consequent mechanical stress inside the pores and at the interface between composite and substrate. This, in its turn, may influence the bond behavior. To expressly evaluate this type of attack and reproduce the effects and the damage due to continuous cycles of salt crystallization/solubilization, a specific weathering protocol was developed, which is based on alternate wetting in saline solution and drying in ventilated oven. This accelerated artificial aging procedure aims at reproducing the natural process to whom a masonry structure reinforced with TRM can be subjected during its lifetime, better than full immersion in salt water. From the point of view of the steel reinforcement, alternate wet/dry conditions are expected to be more aggressive than total immersion. Specimens will undergo this new aging process and will be then subjected to single-lap shear bond tests.
Key publications on this topic
- De Santis S, Stryszewska T, Bandini S, de Felice G, Hojdys Ł, Krajewski P, Kwiecień A, Roscini F, Zając B. Durability of Steel Reinforced Polyurethane-to-substrate bond. Composites Part B: Engineering 2018;153:194-204. DOI: 10.1016/j.compositesb.2018.07.043.
Meriggi P, de Felice G, De Santis S, Roscini F. Durability of Steel Reinforced Grout systems subjected to freezing and thawing conditioning. Fib Symposium on Concrete and Concrete Structures, Parma, Italy, 15 October 2019.