Comparison of 9.5 mm SuperPave and Marshall Wearing I Mixes in ...

67Table 6.4 Comparison of Superpave and Marshall MixesComparison T-statistic CriticalT-valueReject nullhypothesis(Y / N)SP H 100LS MR H 100LS 2.572 2.776 NSP H 100LS MR H 13NS -2.280 2.776 NSP H 100LS MR M 100LS 1.562 2.776 NSP H 100LS MR M 13NS 1.076 2.776 NSP H 13NS MR H 100LS 7.004 2.776 YSP H 13NS MR H 13NS -1.394 2.776 NSP H 13NS MR M 100LS 2.717 2.776 NSP H 13NS MR M 13NS 3.708 2.776 YSP M 100LS MR M 13NS 4.014 2.776 YSP M 100LS MR H 100LS 8.650 2.776 YSP M 100LS MR H 13LS -1.784 2.776 NSP M 100LS MR M 100LS 2.672 2.776 NSP M 13NS MR H 100LS 2.755 2.776 NSP M 13NS MR H 13NS -1.647 2.776 NSP M 13NS MR M 100LS 1.797 2.776 NSP M 13NS MR M 13NS 1.425 2.776 NThese observations demonstrate the complexity of evaluating the rutting potential of asphaltconcrete. In general, it can be concluded from these results that for similar design situations,the Superpave and Marshall mixes produce similar results, although for this data set, the overallrutting potential of Marshall mixes was slightly less than Superpave mixes. It can also beconcluded that too much sand will increase rutting potential. This was clearly shown for theSuperpave mixes where mixes with more than 40 percent natural sand showed more ruttingpotential than mixes with 13 percent natural sand. For the Marshall mixes, two of the threemixes with 13 percent sand showed more rutting potential than the mixes without natural sand.Looking at the data as a whole, other correlations and relationships were observed. Figures 6.1through 6.5 are graphs of rut depths versus design criteria such as asphalt content, VMA, FAA,