Compacted Asphalt Mixture Samples
ASTM International Committee D04 on Road and Paving Materials is currently at work on a proposed moisture conditioning method for compacted asphalt samples that is both time-efficient and allows for the simulation of field conditions. WK32764, Practice for Moisture Conditioning Compacted Asphalt Mixture Samples by Using Hydrostatic Pore Pressure, is under the jurisdiction of Subcommittee D04.22 on Effect of Water and Other Elements on Bituminous Coated Aggregates.
“When a tire goes over a wet pavement, water is initially pushed into the asphalt pores and is then pulled out as the tire lifts off the pavement,” says Ali Regimand, president, InstroTek Inc., and an ASTM member. “Water movement in and out of the voids creates pore pressure within the mixture and can cause liquid asphalt (binder) to strip from aggregates. Loss of bond between aggregates and binder could result in aggregate raveling and premature moisture damage on pavements.”
Regimand says that the testing device described in WK32764 emulates the action of a vehicle tire on a wet pavement by generated pore pressure inside a compacted asphalt sample. Mixtures can be tested for moisture damage susceptibility, prior to laying down a pavement, in an enclosed water filled chamber.
“This test can help engineers design mixtures that are less moisture sensitive and since results can be obtained relatively fast, technicians and agencies can use the device described in the proposed standard for quality control before, during and after construction,” says Regimand.
Technical Information: Ali Regimand, InstroTek Inc., Raleigh, N.C.
ASTM Staff: Daniel Smith