Experimental and Numerical Investigation of Particle Kinematics in Shotcrete

Abstract

The intent of this paper is to identify the basic physical laws governing particle kinematics in a shotcrete spray. This paper presents a governing equation based on Newton’s second law where nozzle and airflow characteristics, and particle features are used to predict impact velocity of the material exiting the nozzle. Experimental values obtained using high-speed imaging measurements on marbles and aggregate particles correlate well with the results of numerical simulations on a simplified spraying system. With the controlling parameters of particle kinematics fully understood, the analysis of the governing equations offers essential elements for nozzle optimization and new mix design investigations. This paper also addresses the necessity of broadening the investigation to the entire spray of particles exiting the nozzle for a complete understanding of the spraying process on placement mechanisms at a process scale.