Green recycled aggregate concrete

The paper presents results of experimental investigation of concrete made with recycled concrete aggregate, low cement content and high content of different mineral supplements. Such concretes belong to “green” or “eco” concretes, since they have less impact on the environment, help in solving the problem of construction and industrial waste disposal, and contribute to the conservation of natural resources. For green recycled aggregate concrete (GRAC) production fine river aggregate and coarse recycled aggregate were used and 50% of cement by weight was replaced by a variety of inert, pozzolanic, and highly reactive mineral admixtures: milled limestone, fly ash, silica fume and metakaolin. Basic properties of ten different concrete mixtures were tested, compared and classified in terms of possible applications. Test results showed that the optimal combination of different mineral admixtures can reduce the basic disadvantage of concrete with high content of mineral supplements – the relatively low strength in the period up to 28-day age, which allows certain structural applications of this type of “green” concrete.