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2016FallShotcreteEMag

Technical Tip of concrete per hour. You have a trailer pump which can exert a maximum pressure of 1100 psi (7.6 MPa) on the concrete and you have 2 in. (50 mm) diameter pumping line. Using only hose, you would have 250 ft (76 m) of hose (Fig. 1) which yields a proportional value of 750 (assuming a 3× multiplication for hose, which varies from 3 to 5× multiplication.) Using a combination of pipe and hose, you would have 200 ft (61 m) of pipe followed by 50 ft (15 m) of hose (Fig. 2) yielding a proportional value of 350. We will omit the reducers because they are the same for both cases. Using these proportional length values, refer to the pumping nomograph (Fig. 3). Beginning with the desired pumping rate of 15 yd3 (11 m3) per hour, trace to the right until you hit the line for the 2 in. (50 mm) pipeline size. Then trace downward until you hit the line for your proportional length value. Trace left from that intersection to the line for 2.5 in. (64 mm) slump, and then upwards to the predicted pumping pressure. The pumping pressure with Option  1, using only hose, will be just above 1000 psi (7 MPa), using nearly all of the pressure available from this Option 1—Hose Only • 250 ft (76 m) of hose 250 ft × 3 (hose multiplier) = 750 proportional ft (230 m) Fig. 1: Proportional length calculation, Option 1 Option 2—Steel Line and Hose • 200 ft (61 m) of steel line • 50 ft (15 m) of hose 200 + 50 ft × 3 (hose multiplier) = 350 proportional ft (110 m) Fig. 2: Proportional length calculation, Option 2 pump, and approaching or exceeding the working pressure of many widely available pumping hoses. Adding in the resistance provided by the line reducers near the pump or any higher multiplier values from the hose based on using dirty Fig. 3: Concrete pumping nomograph. Nomograph courtesy of Schwing America, Inc. Shotcrete • Fall 2016 33


2016FallShotcreteEMag
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