Ultra-high strength concrete made with recycled aggregate from sanitary ceramic wastes - The method of production and the interfacial transition zone

The article describes a new model of ultra-high strength concrete (UHSC) production. It was assumed that the components will be generally available in the concrete plant such as cement, plasticizing admixtures and pozzolanic additives. Aggregate used will be a post-production sanitary ceramic wastes, selected to the two fractions of 0-4 mm and 4-8 mm. The goal of this study was to produce concrete with the highest strength parameters using iterative design method of concrete mix. For so obtained concrete, its basic physical and mechanical parameters were examined, such as: compressive and tensile strength, bulk density, water absorption, water permeability and frost resistance. The examined parameters were compared with results obtained on the reference samples made with the same ingredients, only used aggregate was gravel (0-4 mm) and basalt (4-8 mm). In addition, the interfacial transition zone (ITZ) between cement paste and aggregate (ceramic and basalt) was analyzed, using Scanning Electron Microscope (SEM). On this basis, conclusions on the impact of the ITZ's microstructure on the final characteristics of concrete were made. Own model of cement paste adhesion to the ceramic wastes aggregate was developed.