|To design for a specified service life of a structure when chloride induced corrosion is the likely failure mechanism, engineers usually focus on chloride accumulation in the concrete, in order to predict the build up of chloride able to initiate corrosion (referred to as chloride threshold value or critical chloride content). The limit state related to the corrosion initiation period is achieved when the chloride concentration at the reinforcement level reaches the threshold value. Therefore, the critical chloride content is a decisive parameter for service life estimations. In that sense, the understanding of the mechanisms of depassivation, i.e. the breakdown of the passive layer formed on reinforcement under the action of chloride ions when a certain chloride threshold is reached, is crucial. For this reason, the knowledge of the properties, composition and structure of the passive layer is of fundamental importance. Besides, many attempts have been made to measure the chloride threshold, but construction codes still prescribe 0.4% total chloride by cement weight in the concrete as threshold value. It is important to bear in mind that this value is based on experience with concretes made of Portland cements. In the light of the current developments of non-traditional and sustainable binder types (ternary cement mixes), there is a lack of knowledge with regard to their influence on the protection and onset of corrosion of the future concrete structures. There are, however, some additional ways to improve the durability of reinforced concrete structures exposed to chloride ingress. The galvanised steel and stainless steel are considered solutions to increase the critical chloride content for which the onset of reinforcement corrosion will be initiated. However, an accurate quantification of the extent to which the critical chloride content is increased is difficult and there are no methodologies or data to allow for an appropriate selection of protection techniques.
|Proyectos y convenios en convocatorias públicas competitivas
|Ministerio de Economía y Competitividad
|Gran Empresa (>250)