The evaluation of the influence of mineral additives on the durability of self-compacting concretes

The physical, mechanical and rheological properties of self-compacting concretes enable their application in the construction of bridges which are structures particularly vulnerable to the processes of carbonation and cyclic freezing and thawing. The technology of self-compacting concrete requires an increase in high powder content in the concrete mix, which is obtained by the application of mineral additives. The paper presents test results of the physical and mechanical properties of self-compacting concrete with cement with mineral additives and of the microstructure of its surface layer. The objective of the tests was to evaluate the influence of mineral additives (limestone powder, siliceous fly ash and blast-furnace slag) on the durability of the surface layer of self-compacting concrete subjected to accelerated carbonation and the freeze-thaw process in the presence of de-icing salts. The microstructure of the surface layer of the carbonated concrete was less compact, which was confirmed by the increased surface water absorption and water penetration in the layer in comparison with the non-carbonated concrete. Moreover, carbonated concrete exhibited more significant surface scaling when compared to non-carbonated concrete.