Effect of the coarse aggregate size on pipe flow of pumped concrete

The objective of this study is to find the influence of the coarse aggregate size on pipe flow of pumped concrete. Six different concrete mixes having two mixture proportions (24 and 50 MPa) and three maximum coarse aggregate sizes (10, 20 and 25 mm) were selected and pumped into 170 m and 1000 m pipelines at different pumping pressures. The rheological properties of the concrete and the lubrication layer were measured before pumping, and the thickness of the layer was also experimentally observed with a special sensor. An analytical equation considering the effect of the layer was used to calculate the flow rate. It is worth noting that the pipe flow of pumped concrete is significantly affected by the coarse aggregate size due to the variation of rheological properties on concrete and the layer depending on coarse aggregate size, whereas the thickness of the layer does not change.