Correlating rheological properties to the pumpability and shootability of wet-mix shotcrete mixtures

• This study examines the performance of the wet-mix process in relation to fresh materials’ rheological properties.
• There was no clear relationship between flow resistance and piston pressure.
• A meaningful relationship was identified between torque viscosity and piston pressure.
• The build-up thickness tended to increase as the flow resistance increased.
• Both flow resistance and torque viscosity had no clear relationship with rebound rate.

The pumpability and shootability of fresh wet-mix shotcrete (WMS) mixtures are important factors determining the quality of applied wet-mix shotcrete. Currently, one of the simplest and most accepted methods for estimating the performance of the pumping and shooting process is the slump test. It is well known that the slump test, however, has some limitations in its ability to reasonably evaluate pumping and shooting performance, since it exhibits large variations even among mixtures with the same slump. This paper presents efforts to provide a quantifiable means of estimating the pumping and shooting performance of WMS mixtures in relation to fresh materials’ rheological parameters such as flow resistance and torque viscosity, focusing on investigating the effects of various additives and admixtures. The findings of this study reveal that fairly good statistical correlations exist between torque viscosity and piston pump pressure, flow resistance and build-up thickness, and rebound rate and build-up thickness. By contrast, it was quite challenging to define clear relationships between flow resistance and piston pump pressure, torque viscosity and build-up thickness, and rebound rate and rheological parameters.