The effect of CO2 on cement composites produced with an admixture of waste sludge water from a concrete plant

This article presents the results of a research dealing with the effect of CO₂ on cement composites prepared on the basis of waste sludge water from the concrete plant. The designed formulas R1 and R3 use waste sludge water from the concrete plant as a partial or complete replacement of mixing water in the production of cement composites. The mixing water was replaced by waste sludge water in the amounts of 25%, 50%, 75% and 100%. Laboratory tests that are defined in ČSN EN 1008 standard were performed in order to determine the effect of partial or complete replacement of mixing water. The test specimens were further subjected to the effect of CO₂ in the Lamart laboratory chamber, where the effect of CO₂ was simulated for the period 50 years. Subsequently, the cement composites were tested for their strength characteristics (tensile flexural strength, compressive strength) and subjected to a mineralogical analysis. The results show that the effect of CO₂ will reduce the strength characteristics of the composite compared to the comparative samples.