Oscillatory Flow Behavior of Fresh Concrete in Double‐Piston Pumps

Abstract

Hydraulic pressure signals recorded during concrete pumping are commonly interpreted in terms of pumping resistance or blockage events. However, the waveform generated by double‐piston pumps contains additional information on the coupled response of the pump, pipeline and fresh concrete. This contribution investigates representative pressure signals of four fresh concretes with different compositions, rheological properties, and stability characteristics. The results reveal clearly distinguishable signal patterns, which are discussed in relation to flow table observations before and after pumping as well as accompanying fresh concrete data. The comparison shows that pressure level alone should not be regarded as a robust indicator for pumpability. The observed pressure waveforms suggest that the signal contains information beyond instantaneous conveying resistance, reflecting viscoelastic or viscoplastic response components of the fresh concrete. Since these effects are superimposed on machine dynamics during pumping, a simplified one‐dimensional compression–relaxation setup is proposed to isolate and describe the material contribution.