A commitment to quality is key to successfully completing NPCA’s Precast Plant Certification program. That commitment is put to the test throughout the associated audit, where even the most diligent plants may see deductions for missing requirements found in the NPCA Quality Control Manual for Precast Concrete Plants.

Here are the top 10 most common deficiencies found during plant audits and how they can be remedied:

Topic: Equipment Calibration Records
QC Manual Section: 5.1.3
Issue: Plants fail to calibrate their air meters at the right frequency.
Resolution: Air meters should be calibrated every 90 days. Add an event to your calendar with a reminder alert to perform the calibration.

Topic: NPCA QC Manual
QC Manual Section:
Issue: Plant does not have the most current NPCA QC manual readily accessible for inspectors and plant personnel.
Resolution: The manual is free to download from precast.org/qcmanual. The manual may be printed and stored on-site or a digital copy can be added to a company server that all personnel can access.

Topic: Current Aggregate Certification
QC Manual Section: 2.1.3 or 5.1.1.b
Issue: Plant does not have current aggregate certifications on hand. Evidence of compliance shall be a certification from the supplier that the aggregate meets the ASTM C33 standard.
Resolution: Get in contact with your quarry to obtain the documentation.

Topic: Plant-specific QC Manual
QC Manual Section: 1.1.2
Issue: The plant-specific QC manual is missing pieces or procedures.
Resolution: There are currently 18 elements in that section, mapping out exactly what is needed. The plant’s manual needs to include all components or designate certain components as not applicable to their operations.

Topic: Density and Unit Weight
QC Manual Section: 5.3.3
Issue: Plants don’t perform the test for density (unit weight) of fresh concrete correctly, typically using a strike-off bar, rather than using the strike-off plate.
Resolution: For this test, conducted in the air pot, you must use a strike-off plate.
Critical Notice: This is a critical section. If the test is done incorrectly, it’s a 100% deduction or 1.5 point deduction. Two such deductions assessed in section 5.3 will result in an automatic probation.

Topic: QC Personnel Testing
QC Manual Section: 1.1.3
Issue: The plant’s QC lead and/or backup personnel do not have or have expired certificates of completion from NPCA’s Production and Quality School (PQS). Or they do not have or have expired certificates for applicable concrete testing by ACI Concrete Field Testing Technician – Grade 1, an industry recognized ACI equivalent or an independent third-party professional.
Resolution: PQS courses are offered online. For concrete testing, the plant can take ACI Field Technician Level I (or a nationally recognized equivalent) or contract with a licensed P.E. (on staff or independent) to witness the testing, write a letter and seal it for certification.

Topic: Compressive Strength Cylinders
QC Manual Section: 5.3.5
Issue: The cylinders are made incorrectly.
Resolution: Pay attention to how to make the cylinders for wet cast (ASTM C31), SCC (ASTM C1758) and dry cast (ASTM C497). Hiring an outside service to conduct the testing also may be an option to prevent this deficiency.

Topic: Aggregate Moisture Burns
QC Manual Section: 5.2.2
Issue: Moisture burns are not performed at the correct intervals.
Resolution: If a plant has moisture probes in their bins and mixer, then moisture burns can be performed once a week to check the probes for proper calibration. If they don’t, then moisture burns must be done every day. Add the correct frequency to plant procedures and/or set reminders on the plant calendar.

Topic: Batching Equipment Calibration
QC Manual Section: 3.2.4 or 5.1.3
Issue: Plants have not done their scale calibrations annually.
Resolution: Calibration of equipment and batch scales are required each year. Create a calendar event to have the calibrations performed and have the proper documentation on hand.

Topic: Positioning Reinforcement
QC Manual Section: 4.3
Issue: Plants don’t check the position of the reinforcement for all pieces during the pre-pour inspection. Documentation is signed that it’s been checked and everything was good. The auditor finds, for example, reinforcing steel touching the formwork.
Resolution: Perform the pre-pour inspection on all pieces and correctly document to meet the requirements in the NPCA QC Manual.
Critical Notice: This is a critical section. If you’re going to do it, you might as well do it right. It’s just as easy to do it right as to do it wrong.

How NPCA Can Help

To prepare for a plant audit, whether it’s your first time seeking certification or the unannounced visits for your annual reinspection, NPCA offers resources to help you prepare for the day the auditor walks through the door:

  1. Talk with Engineers: NPCA’s technical services team is available to answer your questions on plant procedures. Call 800-366-7731 to speak with an engineer.
  2. Education: There is no specific education program on certification, but there is education available on the processes that are required within the certification program. You can find courses in myNPCA portal.
  3. Plant evaluations: For a fee, an NPCA engineer will come to your plant and spend the day running through the auditor’s checklist. The engineer can’t tell you exactly what to do to remedy a deficiency but can provide experience and suggest options. You then select which option best fits your business model. Visit precast.org/plant-evaluation-program/ to learn more.