Title: Pumping of Flowable Concrete: Analytical Prediction and Experimental Validation
Author(s): Rami Khatib and Kamal H. Khayat
Publication: Materials Journal
Appears on pages(s): 3-16
Keywords: analytical model; lubricating layer; pressure loss; pumping; viscosity; yield stress
An analytical model was established to predict the pumping pressure of flowable concrete as a function of flow rate, pipe diameter, and rheological properties of the concrete and the lubricating layer (LL). The flow behaviors of the different flow zones across the pipe section during pumping were analytically defined for Bingham materials. The prediction model was validated using a pumping circuit involving 14 high-strength flowable concrete mixtures with slump flow values of 500 to 765 mm. The rheological properties of the concrete and the yield stress, viscosity, and thickness of the LL (the latter determined through reverse regression analysis) were considered as input parameters in the prediction model involving 113 data points in the comparison. The analysis revealed that the thickness of the LL can vary between 2 and 5 mm, and that the predicted pressure loss agrees well with experimental measurements within the range of the tested mixtures.