This paper reports the strength, development and microstructure of high performance concrete in which Ultra Fine Natural Steatite Powder (UFNSP) is used as an admixture. Concrete cubes and cylinders were prepared for compressive strength of 60 Mpa. The effect of varying dosage of ultra fine natural steatite powder is discussed in terms of strength of cubes and cylinders. Specimens of 3, 7, 14, 28, 56 and 90 days strength, and the effect of M-S-H formation in the early ages of concrete are examined. The workability was achieved by incorporating modified polycarboxylic ether as super plasticizer. The micro structure observed with scanning electron microscopy is reported. It is observed that the replacement of ultra fine natural steatite powder of about 5%, 10% and 15% by weight of cement gives a considerable increase in strength during early ages. From 28 days of age changes in the mechanical properties of compositions up to 20% are marginal with respect to the Control Specimen. There is a reduction in mechanical strength of concrete with 25% of replacement of UFNSP. It is observed that change in micro structure is observed for all mixtures at 28 days. © 2014 International Information Institute.