Recycled Coarse Aggregate and Fly Ash Effect on Compressive Strength of Self-Compacting Concrete

The paper presents experimental results of the tests conducted on Self-Compacting Concrete (SCC) with recycled coarse aggregate, and fly ash as filler component. A fine fraction of aggregate originated from a riverbed, while coarse aggregate was obtained either from a riverbed or by crushing laboratory concrete cubes as recycled concrete aggregate. The larger coarse aggregate grains than typical for SCC were used, to highlight the possibility of application in structure elements with sparse reinforcement bars. Four mixtures of concrete were made, in order to compressive strength as the dominant property of any concrete. All of the fresh concrete mixtures displayed proper behavior for this kind of concrete, whereas recycled concrete aggregate induced several challenges. Hardened concrete mixtures showed that beyond the use of natural coarse aggregate, there is the possibility to obtain proper mechanical behavior needed for structural concrete, with moderate amounts of cement. Such an approach paves a way for a cleaner and more sustainable civil engineering practice