Properties of SCC and Flowing Concrete

ABSTRACT: A flowing concrete and two self-compacting concretes were manufactured, at given portland cement content (400 kg/m3) and water-cement ratio (0.45), in order to obtain the same 28-day cube strength. Two mineral additions were used in producing SCC (ground limestone or fly ash). The dosage of a polycarboxylate-based superplasticizer was adapted to produce SCCs with a slump-flow of about 750 mm and a flowing concrete with a slump of 200 mm. Concrete specimens were wet cured at room temperature (20°C). The compressive strength of SCCs were higher than that of the flowing concrete. This can be explained by the pozzolanic activity of fly ash in addition to the cement content; however, ground limestone is not a pozzolanic material and then its acton can be related with a change in the microstructure of the cement matrix caused by the small particles of limestone. The change in the microstructure can also explain why the steel-bond strength is much higher in the two SCCs than in the flowing concrete. The drying shrinkage of the SCCs is substantially the same of that of ordinary flowing concrete, whereas creep is slightly higher in fly-ash SCC than in limestone-SCC or flowing concrete