Control of Rheology, Strength and Fibre Bond of UHPC with Additions - Effect of Packing Density and Addition Type.
This contribution illustrates the effect of additions different in type and fineness and maximum packing density on the macroscopic properties, rheology and bond of steel fibres of UHPC. The results show that the properties of the UHPC investigated were decisively affected by the particle size distribution of the additions rather than the type of material. A new packing density test for fine materials (< 125 μm) was developed to provide calibrated input parameters for the calculation of the maximum packing density of UHPC with different additions. The rheological properties, and therefore fresh concrete workability, were affected by the maximum packing density of the UHPC bulk matrix. The bond strength of steel fibres in a straight pull-out test was affected by addition exchange too. Again, this is explained by packing density effects. Based on packing density calculations as well as SEM and EDX investigations, higher fibre bond strength is explained by a larger proportion of very fine particles in the matrix adjacent to the fibre ITZ which leads to a decrease in the maximum packing density of the fibre ITZ.
Schmidt, M.; Fehling, E.; Glotzbach, C.; Fröhlich, S.; Piotrowski, S.
Book / Congress title:
Proc. of 3rd Int. Symposium on UHPC and Nanotechnology for High Performance Construction Materials