Crack reactivity of ultra-high performance fibre reinforced concrete under the impact and immersion in geothermal water

Abstract

It is well-known that the formation of cracks in concrete affects the durability in aggressive media due to the cracks contributing to the transport processes. However, the processes of interactions inside a crack are not well known and depends on parameters such as the aggressive media composition or the type of concrete. Besides, the self-sealing phenomena of the crack cannot be ruled out that modify the interaction with the aggressive environment. In the present work, the chemical interaction inside the crack of an ultra-high performance fibre reinforced concrete (UHPFRC) containing 45% blast furnace slag (BFS) and a crystalline admixture (CA) additive is analysed after 24 months exposure to the impact of simulated geothermal water (sgw) that contain sulphate and chloride. The obtained results confirm the interaction of the aggressive environment inside the crack, which varies with the deepness of the crack. Self- healing of the external part due to calcite precipitation while leaching of CSH crack wall and precipitation of ettringite inside the crack is appreciated.