The Influence of Mineral Additions on the Rheology of Self-Compacting Concrete

The development of concrete, which need not be vibrated, and which consolidates under its own weight, is a challenge to the building industry. In order to achieve this behavior, fresh concrete must show high fluidity and good cohesiveness. For the propose of evaluating these properties, comes concretes were prepared with a water to cement ratio of 0.45 by alternatively adding two different kinds of acrylic-based superplasticizer to the mixture at a dosage of about 1% by weight of cement. Either fly ash or limestone powder or rubble powder (that is a powder obtained from the recycling process of rubble from building demolition) were used as mineral admixture, in order to ensure adequate rheological properties to the self-compacting concretes in the absence of viscosity modifying agents. Preliminary rheological tests were carried out of pastes in which cement was partially replaced by these fine materials. The fresh concrete properties were evaluated through both the slump flow and the L-box tests. The segregation resistance was also determined. Compressive strength was also measured on hardened concretes after 1, 3, 7 and 28 days of wet curing.