Experimental Investigation of Bed Joint Reinforcement Corrosion in Masonry Mortars

The paper investigates the behaviour against corrosion offered by seven masonry mortar compositions to the reinforcement placed in masonry bed joints. Durability protection was evaluated on the basis of four criteria: carbonation area of the specimens, mass loss of steel, electrochemical potential and presence of chloride ions. Tests were performed against two corrosive environments, with and without chloride ions, and were carried out for three periods: three, six and thirty three months. Two types of steel were used, plain steel and galvanized steel. Moreover, the steel protective action of a corrosion inhibitor, sodium nitrite, was examined. A qualitative comparison approach against prototype concrete-like mortars was used. The results showed that the selected masonry mortars did not exhibit similar properties against corrosion to those of concrete and that the addition of sodium nitrite decrease of the corrosion rate only 5% - 20% did not meaningfully improve durability properties. Nevertheless, the addition of lime in small quantities did not have a negative impact on the mortars’ durability characteristics, e.g. the same average corrosion rate.