Effect of the Aggregates Size on the Rheological Behaviour of the Self-Compacted Concrete

Abstract

The main objective of this study is to split a Self Compacting Concrete by sieving, study the rheological behavior of each fraction and then bind to that of the total concrete to identify the structuration mode of the fresh mixture. Experimental results indicated that concrete, its fractions sieved and its cement paste reconstituted obey to a viscoplastic shear thickening of Herschel-Bulkley type. The state of the shear thickening is directly associated with cement paste; aggregates can amplify or mitigate this situation by arranging them in this matrix. The dynamic couple threshold (indicating of the threshold shear) appears independent of the sieved fraction, that is to say, the maximum aggregate size and compactness of the mixture, whereas the apparent viscosity generally decreases with the decrease of these rheological parameters. The resistant torque in the concrete fractions is linearly related to the resistant torque in the total mixture. That explains why the rheological behavior of a Self Compacting Concrete and its fractions are governed by the same mode of structuring and it is only the scale (size of the aggregates) which differs.