In some porous media, such as mortar, reactions take place between the fluid (e.g. water) and the matrix material (e.g. cement). When combined with partially saturated conditions, this leads to highly nonlinear seepage, which may strongly affect the transport of secondary species through the material. In the context of mortar, transport of chloride ions are of particular interest. In this project, we combine XRCT-imaging and numerical modeling to describe these complex phenomena.
The durability of reinforced concrete structures is significantly affected by the corrosion of rebars, which can induce cracking and spalling of the concrete cover. Once the rebars are exposed to external environment, the corrosion process is accelerated which leads to rapid cross section loss of the steel. To recover the original safety factor, structural repairs must be performed. Up to date the most common repair method is to splice an additional piece of reinforcement to the corroded rebars to compensate for the area reduction, however this is a time consuming and costly process.
On that sense Engineered Cementitious Composites (ECC) appears to be an attractive option for such repair applications. This kind of materials present high ductility and the formation of closely spaced multiple cracks with opening only about 100 μm until the ultimate tensile strength is reached. This means high deformation capacity, high energy absorption and excellent durability (by controlling the crack width to limit water/chemical penetration). However, as a still new material much is still to be discovered to understand how those materials can limit the corrosion process or fix it for structures already heavily corroded.
Therefore, on my research interests I target to understand by which means the ductility and associated cracking behavior of ECC’s can affect the corrosion process. Moreover, the aim is also to evaluate the effectiveness of using this material as repair methods, being a key challenge to understand the joint between old and new concrete. Not only mechanical tests are part of the investigation, but also understanding the chloride transport and binding mechanisms and microscopical observations of rust formation and crack propagation.