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Long-term corrosion investigation of mortar embedded wall-ties exposed to atmospheric corrosion

Paper Number: 33
Author/s: B. Jardim do Nascimento1, I.A. Chaves1, M.J. Masia1 & R.E. Melchers1
Organisation: Centre for Infrastructure Performance and Reliability, The University of Newcastle, Callaghan, NSW 2308, Australia

Abstract

Metal ties provide structural capacity to masonry cavity or veneer wall construction. Corrosion of such wall-ties when embedded in the mortar can be severe and consequently lead to a premature structural failure of the wall. Available atmospheric corrosion models can be used to predict loss of structural capacity however these are based on short term data and only consider deterioration for the cavity exposed ties. Yet, corrosion within the mortar can be more severe and rapidly jeopardise the tie’s longevity. Moreover, the existing atmospheric models are sensitive to parameters changes and bound by theoretical assumptions which in turn can result in an uncomfortable level of uncertainty of the predictions. This paper describes an empirical long-term framework to investigate the corrosion of mortar embedded galvanised (300g/m2 and 470g/m2) and 316L stainless steel wall-ties. Three different types of ties, each embedded in three different classes of mortar with increased cement content, are to be exposed to naturally aggressive as well as artificial salt spray environments. Expected differences in deterioration mechanisms as well as capacity loss are discussed within.