Abstract
Because of their high volume of paste, self-compacting concretes (SCCs) cost more expansive than ordinary concrete and exhibit more shrinkage values which increases their susceptibility to cracking and may alter their durability performances. For economical and environmental considerations, many studies were done these last years on the use of mineral admixtures as filler in SCCs. The aim of this paper is to contribute to the characterization and the understanding of shrinkage of SCCs where Portland cement is partially substituted by slag, fly ash or metakaolin. The shrinkage from casting to 360 days of aging of four SCC mixtures based on CEM I 52.5N, CEM III/A 52.5L (slag cement), CEM V 42.5N (blended cement containing fly ash and slag) and CEM I + 15% of metakaolin is investigated. Experimental tests include plastic, autogenous, free drying and restrained shrinkage. Results show that shrinkage depends on the mineral admixture type and more particularly on the developed microstructure. Replacing 15% of Portland cement by metakaolin increases the shrinkage at the plastic state and decreases it significantly at the hardened state in free drying conditions. The use of CEM III instead of CEM I involves an inverse behavior. In restrained conditions, mineral admixtures seem to reduce the age of crack initiation. However, the crack opening is reduced by at least a factor of 2. The results are in a good agreement with water porosity, mass loss, compression strength and thermal measurements.