Re-curing of calcium aluminate cements post contact with molten slag

Calcium aluminate cements (CAC) are widely used for the production of refractory concretes that are able to withstand extreme temperatures. During exposure to such temperatures, the main hydration phases revert to mayenite, calcium aluminate and calcium dialuminate. Many investigations focused on the description of this mechanism and how it affects the remaining mechanical properties of the concrete. However, subsequent contact with air humidity after high temperature exposure further modifies the composition of the cement paste. The effects of re-hydration on the pore network and mechanical properties of concrete are critical to the design of durable systems under repeated exposure to high temperatures, as well as assessing the remaining quality of damaged structures. Yet such effects remain poorly understood. This research focuses on the use of CAC as a compatible protection layer to concrete made with ordinary Portland cement (OPC) in order to sustain infrastructure in industries which may have occasional or even constant high temperature spills (such as steel, aluminum, petro-chemicals and others). To achieve such goal, slabs with one layer composed of CAC mortar and a second layer made of OPC mortar will be subjected to contact with molten glass at 1530°C followed by exposure to ambient moisture in a fog room. The microstructure of these samples will then be studied and compared.