The Influence of the Fineness of Mineral Additions on Strength and Drying Shrinkage of Self-Compacting Mortars

Self-compacting concretes are extremely fluid concretes that can be placed into formwork without vibration. They are characterized by the presence of mineral additions which influence considerably their behavior in fresh and hardened states. This paper reports the results of an experimental study on the influence of Ground Granulated Blast Furnace Slag (GGBFS) and natural pozzolana (NP) and the effect of their fineness on the compressive strength and shrinkage of self-compacting mortars. Each addition was ground to three finenesses 350, 420 and 500 m2/kg. The cement is substituted by 0%, 15% or 30% of GGBFS. The water to binder ratio was kept low at 0.40; cement content and superplasticizer were maintained constant for all mortars mixtures. The results show that the substitution of cement by mineral additions (slag and natural pozzolana) generates a reduction of the total shrinkage (at 28 days) and compressive strength of self-compacting mortars, whatever the fineness of the addition. The study also showed that the increase of the fineness of the natural pozzolana gives an increase in both drying shrinkage and compressive strength. However, the increase of the fineness of slag decreases slightly the shrinkage and the compressive strength of self-compacting mortars.