Effect of the Mineral Admixtures on Pipe Flow of Pumped Concrete

Abstract

The objective of this study is to investigate the effect of the mineral admixtures on pipe flow of pumped concrete through analyzing the properties of lubrication layer playing a dominant role to facilitate concrete pumping. Concrete mixtures incorporating blast furnace slag (BFS), fly ash (FA) and silica fume (SF) were selected with three different replacement ratios for each case and pumped through 170 m circuit. The rheological properties were measured before pumping and the thickness of lubrication layer was also experimentally observed with a special sensor, ultrasonic veloc-ity profiler (UVP). An analytical equation considering the effect of the layer was adopted to calculate the thickness of the layer and to compare with full scale pumping results. The lubrication layer of BFS and FA indicated almost constant value regardless of replacement ratios but varied with SF mixtures. The concrete incorporating BFS or 5% SF represented satisfactory improvement of pumping efficiency.