When it comes to ensuring the composition of a paved asphalt road meets quality standards, plant operators and contractors alike influence the outcome at every stage of the process.
“Quality starts long before you’re going to get any test results,” says Debbie Schwerman, executive director at the Wisconsin Asphalt Pavement Association.
From the moment aggregates are selected to final density testing in the field, each phase builds on the last. And a breakdown at any point can compromise the entire hot mix pavement.
Below are five key areas where plant operators and contractors should focus to maintain quality from start to finish.
The biggest key for the quality of the mix is going to be communication, communication and communication.
STEP ONE: SELECTING AND HANDLING AGGREGATES
The asphalt process begins with aggregates, where early decisions set the foundation for everything that follows.
Clean, high-quality aggregates depend on how they are crushed, processed, stockpiled and transported to the plant. Once there, they move through equipment that determines weights and composition before mixing.
Quality issues can arise when incorrect proportions are introduced due to miscalibrated scales, damaged screens, operational errors or “electrical chatter.”
Even small inconsistencies at this stage can carry through the entire process, affecting mix performance long before testing begins.
STEP TWO: DRYING TO REMOVE MOISTURE
Once aggregates are properly sized and proportioned, the next critical step is removing moisture. This is one of the most common sources of variability in asphalt production.
Moisture affects asphalt binder content, and even slight inaccuracies can translate into hundreds of pounds of moisture-laden mix in the field. Calibration issues or improperly used test weights can further skew results.
If drying drums are clogged with debris or excess moisture, they cannot properly lift and drop aggregates, leading to clumping that coats the mix. Production rate, drum angle and temperature must all be carefully managed.
Left uncorrected, moisture issues can compromise both consistency and long-term pavement durability.
STEP THREE: ADDING ASPHALT BINDER
With aggregates dried and stabilized, the focus shifts to combining them with asphalt binder. This is where precision becomes even more critical.
Inaccurate binder amounts can result from miscalibrated pumps, improper temperatures, blocked filters or moisture inconsistencies.
Storage introduces additional risks. If mix does not flow properly through silos, segregation can occur due to mechanical issues, rapid loading or temperature fluctuations.
At this stage, even minor inconsistencies can undo earlier efforts to maintain quality.
STEP FOUR: LAB TESTING
After production, verifying that the mix meets specifications depends on accurate and consistent lab testing.
Samples must represent the full batch and be transported carefully to prevent segregation. In the lab, certified technicians must use properly calibrated equipment and maintain consistent procedures.
“You need them to be very thorough, paying attention to all the little details,” Schwerman says about lab technicians. “They need to be organized and have really good communication skills.”
Reliable testing ensures that issues are identified before they impact performance in the field.
STEP FIVE: CONSTRUCTION
Even with a properly produced and tested mix, quality can still be lost in the field if placement and compaction are not carefully managed.
Contractors must keep pavers moving to maintain consistency, often using material transfer devices. Mix stored on-site should be remixed to maintain proper temperature and uniformity.
To maintain asphalt quality during placement, contractors should focus on:
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Keeping pavers moving continuously to avoid temperature fluctuations and segregation
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Using material transfer devices to maintain consistent flow and reduce variability
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Monitoring mix temperature closely to ensure proper compaction and performance
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Remixing stored material to maintain uniformity before placement
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Timing density testing correctly to avoid inaccurate readings from heat or moisture
After paving, testing for in-place density is critical. Proper density reduces permeability, slows oxidation and improves resistance to rutting and cracking, lowering lifecycle costs.
However, environmental factors such as rain can affect testing accuracy, and cutting cores too early can deform pavement.
At this final stage, proper execution ensures that the quality built throughout the process is fully realized in the finished road.
COMMUNICATION ACROSS ALL STEPS
Throughout all stages, plant operators, contractors and testing technicians must communicate to identify and resolve issues early.
“The biggest key for the quality of the mix is going to be communication, communication and communication,” Schwerman says.
From plant to lab to jobsite, asphalt quality is not controlled in a single step; it is built through every stage.
Schwerman shared these insights at the CONEXPO-CON/AGG 2026 session, Asphalt Quality Essentials: From Planning, Production, and Into Construction. Purchase On Demand Education Access to listen to recordings from the show.
PHOTO CREDIT: SHUTTERSTOCK/STOCKR
