Specification Corner

Colorado DOT
Colorado Procedure 52 (Contractor Asphalt Mix Design Approval Procedures) was revised to add a note that "the RAP aggregate bulk specific gravity will be back-calculated using an assumed average aggregate water absorption of 1.01%. The corresponding assumed aggregate asphalt absorption will be 0.61%.” This revision is in line with AASHTO R 35.

Florida DOT
In January 2019, a Delta Tc requirement will be added to the FDOT asphalt binder specification. Asphalt binders aged with the PAV for 20 hours must have a Delta Tc greater than or equal to -5.0°C. Also, REOBs/VTAEs will be limited to 8.0% max.

Massachusetts DOT
Starting in 2019, MassDOT intends to standardize its HMA QA specification (Section 450) from the standard special provision, which has been used for the last 10 years.

Utah DOT
Utah added a longitudinal joint density specification for hot mix asphalt paving and has noticed good results with it so far. The longitudinal joint target density is 91.5% of Gmm with a lower limit of 89.5%. Six-inch cores on the joint every 1000 feet are tested.

Utah changed its micro-surfacing specification to use only natural or synthetic latex for the polymer. A requirement of 3% by weight of the binder has not changed. Utah is getting good results, and the projects look great so far.

Utah removed the Direct Tension Test (DTT) for modified binders for all projects next year because of the cost, availability, and service of the equipment. The test has been replaced with the Delta Tc parameter of -1.0°C for one PAV cycle with a compliance limit down to -2.0°C and a minimum stiffness on the first Bending Beam Rheometer (BBR) beam of 300 MPa. Elastic recovery requirements have also been increased. These changes were made to give us the same binders we currently have with the use of the DTT. We believe the DTT has kept REOBs out of our market.