Recent research into velocity of the material stream shot from the nozzle is approximately 60 to 80 mph (97 to 129 km/h) in the middle of the stream. Outer portions of the stream are slowed and show speeds of about 45 mph (72 km/h). Here’s a link to the Technical Tip published in the Fall 2013 Shotcrete magazine that provides more complete documentation of the research: www.shotcrete.org/wp-content/uploads/2020/01/2013Fal_TechnicalTip.pd.