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State of California, Department of Transportation - page 6 / 52





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Virgin Aggregate - Natural occurring gravel, cobble or rock formations that have been screened or crushed into various sized aggregates. Aggregate sources can be classified into two different types, alluvium or hillside deposits.

Lime Slurry Treated Aggregates A process that mixes aggregates with slurry comprised of one part dry hydrated lime and three parts water. The mixing of the aggregates and slurry is performed in a pugmill. Aggregates for each bin or stockpile are treated separately then allowed to set (marinate) for a minimum of 24 hours before being processed through the AC plant.

Supplemental Fine Aggregates - Includes baghouse fines, dry hydrated

cement, fly ash discussed later in

or limestone dust. this manual, for each

Introduction type of plant.




lime, portland aggregates is

Aggregate Qualities - Desirable characteristics specified in the contract documents, such as well graded, crushed or natural, surface texture, durability, cleanness, density, absorption, abrasion resistant and affinity for asphalt.

AC Mix Designs - Aggregate, supplemental fines, asphalt binder and/or antistrip additives are received from the Contractor along with an X-Value or Target Value letter indicating the desired gradings and bin percentages for the proposed mix design. Depending on the type of project, Caltrans laboratories or Private laboratories may perform all the testing to prepare a mix design for the Contractor. Many different tests are performed before the mix design is approved and this may take up to a couple of weeks. At this writing, Caltrans only recognizes mix designs created using the Hveem method.

Certificate of Compliance Each load of asphalt binder is to be accompanied by a “Certificate of Compliance”. The certificate shall include the shipment number, type of material, specific gravity of material, refinery, consignee, destination, quantity, contract or purchase order number and date of shipment. The certificate shall include a statement that the material complies with the Contract Special Provisions and the Standard Specification and must be signed by the vendor or the vendor’s representative. Any asphalt binder furnished without a Certificate of Compliance shall not be used in the work until the Engineer has had sufficient time to make appropriate tests and has approved the asphalt for use. Even with a Certificate of Compliance the asphalt binder must be sampled and tested on a daily basis.

Paving Asphalt - Asphalt is the residue that remains after crude oil is refined. Caltrans uses asphalts with an AR designation, such as an AR-4000. The AR (Aged Residue) grading system uses the Rolling Thin film Oven to condition the binder sample. This procedure uses heat and air on a moving film of semi-solid asphalt. The effects of this test are determined by measuring the properties of the asphalt binder before and after the treatment. The number designation after the AR, is the viscosity of the binder.

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