Effect of Aggregate Crushing on Fresh Concrete

The main results of this work indicate that it’s possible to measure changes in fresh concrete rheological properties if manufactured fine (0/2 mm) aggregate produced by different crushing processes and containing normalized amount of fines is analysed in concrete. Workability increase due to replacement of a cone crusher with a vertical shaft impactor (VSI) for the last step seems to be of a higher order than changes due to VSI tip speed. Those factors were found to have no effect on rheological properties of the corresponding matrix (filler modified cement paste). It was found that most of the convenient fine aggregate characterization parameters can give an indication of the 0/2 mm crushed sand performance in concrete with respect to rheology. However the order of relation is rather limited and none of them can be used as a fundamental parameter. Loose and compacted packing measurements tend to show a lot better correlation. However the correlation is not perfect and based on the results acquired within the research two other parameters by combining packing and specific surface concepts have been proposed.