New Jersey

Department of Transportation

Standard Specifications

for Road and Bridge Construction

2007

NJDOT C-1 – Determining Yield of Concrete Produced by
Continuous-Mixing-Type Truck Mixers

1. Scope. This test method is used to determine the yield of concrete that is proportioned volumetrically in a continuous-mixing-type truck mixer.
   
   
2. Apparatus. The apparatus will consist of a 1/4-cubic yard container having dimensions of 36 × 36 × 9 inches. Construct the container using materials that do not become deformed when filled with concrete.
   
   
3. Procedure. Perform the following steps:
   
   
   1. Set all controls of the mixer unit at the settings approved for the mix design being checked.
   2. Activate the mixer and discharge sufficient material to fill the mixing auger assembly and discharge chute. Then deactivate the mixing unit.
   3. Reset cement meter to zero and reactivate the mixer and discharge material into the 1/4-cubic yard container until it is level-struck full, making provision for the material settling into all corners.
   4. Record the count as shown on the cement meter.
   
   
4. Calculation. Calculate the cement count that is equivalent to the amount of cement specified in the mix design for 1/4 cubic yard. Calculate the yield by dividing the actual cement count by the specified count and multiplying by 100. The result will be 100 ± 2 percent.
   
   
5. Report. Report the yield to the nearest 0.1 cubic yard.