Nonpozzolanic fillers are frequently used to optimise the particle packing and flow behaviour of cementitious paste in self-compacting concrete ( SCC ) mixes. The influence of finely ground limestone and crushed limestone dust on the properties of SCC mixes in the fresh and hardened state are discussed. Mixes were prepared using poorly graded crushed limestone aggregate. To compensate for the lack of fine material in the crushed sand, a viscosity agent was added to the mixtures. The results indicate that finer and better-graded limestone dust significantly increases the deformability of the paste. When a high volume of this filler was added to the SCC mix, the required self-compacting properties were achieved at a lower water/(cement+filler) ratio, and it also appeared that the addition of filler improves the 28-day compressive strength of concrete mixes due to the filler effect and improved fine-particle packing. 31 refs.