Abstract
Accurate measurements of specific gravity and absorption of coarse and fine aggregates used in hot mix asphalt are essential for proper mix design. The specific gravity and absorption characteristics are often measured in accordance with AASHTO standard methods (AASHTO T84 and ASHTO T85). The results from these tests are strongly dependent on the experience and expertise of the operator. Due to the subjective nature of the AASHTO T85 test and the considerable testing time, Idaho Department of Transportation (ITD) is seeking alternative methods to determine these parameters with greater reliability. A recent research study (Project ITD RP 252) developed a correlation between results from a CoreLok device and the generally accepted AASHTO T84 procedure for fine aggregates. The CoreLok method is quick, reliable, and provides consistent and repeatable results. Tests using the CoreLok device can be completed within 45 minutes compared to the AASHTO T85 method which takes nearly 36 hours. The models from Project RP 252 predict the AASHTO T84 values of specific gravity and absorption using the CoreLok method for typical fine aggregates used in Idaho. This study examined and developed similar correlations between the AASHTO T85 and CoreLok results for coarse aggregates as well as blends. Instead of establishing separate models for coarse and fine aggregates is study developed trends for all mixes of aggregates.