Today’s hot mix asphalt (HMA) contractors are responsible for the quality of their mixes, although this has not always been the case. In the old days, DOT (or other agency) personnel performed all the testing. Gradually, states shifted the responsibility for quality control (QC) to the contractor.
As this shift occurred and production of HMA became more complex—tougher mix design requirements, new ingredient materials and real-world economic considerations—contractors needed more information about their materials.
“In the old days, contractors sent their samples to commercial testing labs for analysis,” says Scott Quire, Chief Materials Engineer and Quality Control Manager for H.G. Mays Corporation, a Kentucky paving contractor. “This practice was costly and took quite a bit of time.
“But in recent years, contractors have begun developing their own QC capabilities and have steadily been adding onsite testing facilities to their operations. Contractors found that they could privatize their QC operation by hiring certified technicians like me who either worked for the state DOT or independent laboratories and had expertise in HMA mix design and testing.”
Contractors have recognized a need to train their technicians. “As technology has grown more complicated, the need for qualified personnel to utilize the sophisticated equipment has become critical to a producer’s operation,” says Quire. “You have to have an intensive quality control program. You find yourself training and retraining technicians to work in the lab. In our case, we have in-house schools. We train our people on the proper use of each piece of equipment and we also teach our technicians to adjust the mix to meet the specifications.”
Most agencies require that personnel involved with materials sampling and testing be certified. Although programs vary from state to state, a typical certification program might include:
- Basic inspection functions
- Plant and paving operations
- Sampling techniques
- Maximum specific gravity determination
- Compaction and analysis of mixture specimens
- Asphalt content testing
Return on Investment
Contractors have found that in-house testing is not only beneficial from a production standpoint but it can be profitable. “With a field-lab facility, you can test on-the-fly and make adjustments to the mixes as needed. This results in higher quality mixes and can also lead to receiving performance bonuses. The significance of adequately trained technicians cannot be overstated,” says Quire.
Contractors’ labs provide another benefit. Daily QC testing generates tremendous amounts of data. This information can be used by government agencies to evaluate mix performance, testing procedures and acceptance standards. By analyzing this data, industry and agency leaders can make informed decisions on test types and frequency and specifications parameters.
Contractors have learned that having the information to make timely adjustments to their mixes is good business. What started as an agency requirement, now allows them to produce more economical mixes and provide the durable pavements that the traveling public deserves.