Sulfate Resistance and Microstructure Changes of Sustainable Self-Compacting Concrete Containing Micro to Nano Waste Materials

The concrete microstructure may change the resistance of concrete to the penetration of aggressive substances from the environment into the concrete body. Incorporating micro-to-nano waste materials, such as Limestone (LS), Fly Ash (FA), Glass Powder (GP) and Kaolin (K), can modify the concrete microstructure and increase its chemical resistance. This study investigated the use of four waste material formulations with different scales in medium-strength (at the range of 25-45 MPa) sustainable Self-Compacting Concrete (SCC), and its sulfate resistance and microstructural changes were studied. Ordinary Portland cement was replaced with 40% waste materials at the microscale, and 4% at the microscale to nanoscale. The analysis of the performed tests showed that the type and scale of the cement replacement material significantly affected the durability performance of SCC under magnesium sulfate exposure. In addition to the fresh properties, the flowability improved significantly with the use of waste materials at the microscale, while the passing and segregation resistances of microscale to nanoscale waste materials improved more than microscale replacement. The tests performed showed that 4% FA demonstrated a better mechanical performance and durability in a magnesium sulfate environment.