Recycled concrete in weak acidic environments

摘要

Literature often concludes that the lower mechanical properties of recycled concrete, compared to standard concrete, is unfavourable for the durability in aggressive environments. The agricultural industry is an environment where concrete floor slabs and walls are confronted with weak organic acids. An investigation was set up to determine the resistance of concrete made with coarse recycled concrete aggregates (0-75%), against these acids. In this research two different qualities of recycled aggregates were used: the first originated from road demolition and contained porphyry as main aggregate, the latter originated from mixed demolition and contained mainly limestone. A reference concrete mixture and six different recycled concrete mixtures were made. All seven concretes mixtures were exposed to three different acids: acetic, tartaric and citric acid. Beside the acidic resistance tests, the workability, the fresh and hardened density and the water absorption both by capillarity and submersion, were determined. The results show that the increase of acid soluble material increases the resistance of concrete against erosion due to weak acids.