The Quality Control Department of Whitaker Contracting is responsible for the asphalt mix design and production testing of hot mix asphalt (HMA).

            HMA consists of bitumen, aggregate and recycled asphalt.

• Bitumen (liquid asphalt) is a by-product of refined crude oil. Sometimes mistakenly referred to as Tar, which is refined from coal. The physical characteristics of bitumen changes with temperature. When it is cold, bitumen has the consistency of hard wax. To make HMA, bitumen must be heated to 325 degrees and has the viscosity of syrup. Bitumen comprises 3.5-6.5% of the HMA.
• Aggregate in our local area used to make HMA includes crushed limestone, sandstone, granite, gravel or slag (a by-product of steel foundries). The crushed aggregates are screened into different size fractions and recombined in a blend determined by the HMA mix design. Virgin aggregate comprises 70-80% of the HMA.
• Recycled asphalt (RAP) is old HMA milled from an existing HMA pavement and further processed by crushing and screening. The bitumen in RAP is “harder” than virgin bitumen, due to oxidation, and can only be added to new HMA in limited amounts. RAP comprises 15-25% of the HMA.

Hot mix asphalt produced by Whitaker Contracting is tested by technicians certified by the Alabama Department of Transportation (AL DOT). Levels of certification include Asphalt Mix Design Technician, Laboratory Technician, Quality Management Technician and Roadway Technician.

·        Asphalt Mix Design Technicians proportion the HMA blend of bitumen, aggregate and RAP to meet the specifications of our customers.

·        Laboratory Technicians sample the HMA from the production plant and test it for specification compliance. Testing parameters include temperature, % bitumen, % air voids in a compacted specimen and aggregate gradation.

·        Quality Management Technicians review test data and make changes to the production process when necessary.

·        Roadway Technicians test the density of the HMA pavement and set the roller patterns of the asphalt rollers to assure that the pavement is adequately compacted.

The HMA laboratories of Whitaker Contracting are equipped with the latest technologies in HMA testing including nuclear AC and density gauges, Superpave gyratory compactors, and NCAT ignition furnaces.

Whitaker Contracting Corporation has a history of commitment to quality and continues that commitment by striving to produce the highest quality HMA available.