4. Mix Production

4.9 Weighing and Loadout

From the temporary storage silo, asphalt mix is deposited into trucks ready to be hauled to paving sites. (See Chapter 6 for truck loading procedures.) The quantity of mixture delivered from plant to paving site can be determined by any of three methods:

• Using a batch plant’s automatic recording system.
  • The system records the accumulated weight of individual batches dropped directly into a truck from the pugmill. The internal plant scales should be calibrated and certified to use this method successfully.
• Using load cells attached to the support legs of a storage bin
  • he load cells collectively accumulate the subtraction of weight from the bin as a truck is loaded.
  • Load cells are calibrated and certified as accurate.
• Weighing loaded trucks on scales.
  • The scales directly indicate the tare weight of the truck and net weight of the mix.
  • The scales should be level, horizontal, and of sufficient length to weigh all truck axles at one time. The most common type of truck scale used is the beam scale (see Figure 55).

Source: National Asphalt Pavement Association
Figure 55. Truck Scale Under Storage Bins

The accuracy of any truck scale or weigh system should be checked periodically. Random truckloads selected throughout production and weighed on an alternative, certified scale provide for a good check on the accuracy and calibration of the weigh system being used.

The accuracy of any truck scale or weigh system should be checked periodically.