Comparative Investigations on Ultra-High Performance Concrete with and without Coarse Aggregates

SUMMARY In the present paper UHPC was produced with crushed basalt with the particle size from 2 to 5 mm. The compressive strength has reached the same magnitude as reactive powder concrete (RPC) in which the maximal aggregate size is smaller than 1.0 mm. The use of the coarse aggregates led not only to the decrease in cementitious paste volume fraction, but also to some changes in mixing process and in mechanical properties. UHPC containing coarse aggregate was easier to be fluidised and homogenized. The mixing time can be shorter than that for RPC. The both tested UHPC exhibited a similar behaviour under compressive stresses, except somewhat different modulus of elasticity and strain at peak stress, which related to the stiffness of the used aggregates. The lower paste volume fraction and the hindrance of the stiffer basalt split resulted in a lower autogenous shrinkage of UHPC containing coarse aggregates.