Automatic Devices for Determining the Bulk Specific Gravity of Fine Aggregates
Recently, there has been some development of alternative procedures to determine the specific bulk gravity of fine aggregates. The recent surge was initiated with urging by the Federal Highway Administration (FHWA), and its funded study completed by the National Center for Asphalt Technology (NCAT). NCAT’s prototype device ignited interest among the different equipment manufacturers to develop an accurate means of determining the bulk specific gravity of fine aggregates. At the moment, there are currently three articles of equipment, identified by the FHWA (Hall, 2003), that demonstrate promise to be utilized as a substitute for AASHTO T-84: 1) CoreLok AggPlus System, 2) Thermolyne’s SSDetect (advertised and sold by Pine Instruments), and 3) NCAT’s Surface Saturated Drier (manufactured by Gilson Equipment).
The research project currently underway at RAPL is to evaluate each of these pieces of equipment and compare the results to the AASHTO T-84. The initial comparison will be based on testing several natural sands typically used in HMA design in New Jersey. On confidence has been developed with the new equipment and test procedures, several manufactured sands will be evaluated. The main goal is to identify a test method/equipment that provides repeatable and reliable bulk specific gravity parameters for HMA design.
Figure 14 shows the SSDrier, Figure 15 shows the SSDetect, and Figure 16 shows the AggPlus System.
  Figure 16 – AggPlus System for Bulk Specific Gravity of Fine Aggregates |
