Material Plant Quality Program

The Material Plant Quality Program (MPQP) provides procedures to approve proportioning material plants that produce materials for Caltrans construction projects according to the MPQP Manual and Caltrans specifications.

The following material plants require approval (but are not limited to):

  • HMA batch and continuous
  • Asphalt rubber binder
  • Portland cement concrete batch
  • Precast batch
  • Cement treated base
  • Volumetric mixers (such as for polyester concrete, rapid strength concrete, slurry seal)

All weighing devices (for example, truck scales, weigh bridges, hopper scales) shall be mounted on concrete slabs in accordance with Caltrans specifications.

All safety guards, rails, fire extinguishers, eye wash stations, and other implements shall be in place and functioning in accordance with Caltrans specifications.

Obtaining Plant Certification

Contact the appropriate Caltrans district weights and measures coordinator (WMC) to inquire about approval requirements for your plant and schedule an appointment at least 2 weeks prior to the requested date. Priority will go to those proportioning material plants producing materials for a Caltrans project. The WMC will witness the calibration of the proportioning material plant and approve it if deemed compliant with Caltrans requirements. A scale company (Registered Service Agency) is required when calibrating.

California certified traceable masses shall be present with enough mass to prove the scales. The county WMC may be contacted to prove the scales for the county at the same time.

External Resources

For any additional questions contact the HQ MPQP Coordinator at