Ceramics-Silikáty

Two difficult to utilise wastes - glass sludge, obtained from processing glass, and concrete sludge, obtained by washing concrete trucks, were used. In the sustainable concrete composition, glass sludge was used as a replacement for cement, varying from 5% to 30% and concrete sludge was used as a filler. Additionally, sand, dolomite, a superplasticiser, a crystallising additive, and an air-entraining additive were used and a consistent water-to-binder ratio was maintained. The content of the entrained air, porosity parameters, compressive strength, water absorption, density and sorptivity index for the hardened samples were measured. The resistance to freezing was assessed by the volumetric method and scaling tests in a de-icing salt solution to determine the mass losses, while the damage degree of the internal structure was evaluated. The results suggest that the synergistic interaction between the glass sludge and the crystallising additives promotes pore healing, enhancing the closed porosity and reducing the open porosity at glass sludge levels of 20% or less. The findings indicate that glass sludge has no detrimental effects on the frost resistance qualities and may even enhance them if up to 20% of cement is substituted with glass sludge.