Evaluation of methods for determining bulk specific gravity of Hma specimens
In this study, comparisons were made on the methods for bulk specific gravity measurements of rutted and unrutted Hot Mix Asphalt (HMA). Bulk specific gravity determination was performed using three methods: Water Displacement(TM), Parafilm(TM) and Corelok(TM). The evaluations were made on a total of sixty-two sets of two or three specimens, four different mix designs for rutted specimens, and three different mix designs for the unrutted specimens. The bulk specific gravity test results were compared for similarity of the methods and repeatability of the measurements for each method. Analysis of the data showed that (1) for unrutted specimens, the bulk specific gravity measurements by Water Displacement(TM) method are slightly higher than the Corelok(TM) method, and measurements by Parafilm(TM) method are significantly lower than the other two methods; (2) measurements by Corelok(TM) and Water Displacement(TM) methods for rutted fine graded mixes are closer to each other than those for rutted coarse graded mixes; (3) two-way ANOVA analysis using means of bulkl specific gravity measurements for both rutted and unrutted specimens shows that, there is a statistically significant difference between the measurements made by Water Displacement(TM), Parafilm(TM) and Corelok(TM) methods, and (4) based on a two-way ANOVA and Friedman test analysis, the Water Displacement(TM) measurements are more repeatable than Corelok(TM) for rutted and unrutted specimens. Additionally, for the unrutted specimens Water Displacement(TM) and Corelok(TM) are more repeatable than those made by Parafilm(TM).
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