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

% Limestone71100.080.060.040.020.00.05.00 7.00 9.00 11.00 13.00 15.00 17.00 19.00Rut Depth (mm)MR HVY 100% LS MR MED 100% LS MR HVY 13% NS MR MED 13% NSSP HVY 100% LS SP MED 100% LS SP HVY 13% NS SP MED 13% NSSP LOW 100% LS SP LOW 50% NS SP LOW 64% NS SP LOW 100% LS (MOD)Figure 6.5 Rut Depth vs Percent Limestone Sand6.4EVALUATION AND COMPARISON WITH OTHER STUDIESComparisons of results from this research with those of past studies are divided into thefollowing sections: fine aggregate angularity, comparison of Marshall and Superpave mixmethods, voids in the mineral aggregate and APA testing results.Fine aggregate angularity. It was stated by both Huber (1998) and Casanova (2000) that itunclear if FAA is a fair and accurate indication of pavement performance. Huber found nocorrelation between FAA and rut depth results. However Casanova showed a correlationbetween FAA and rut depth measurements, but also found that FAA tests may not be enoughsince it tended to reject strong material and accept weaker aggregates. An R 2 value of 0.67 wasfound when comparing FAA values with rut depths for this research. This values shows thatthere is, at the least, a slight correlation between rutting potential and FAA, but the correlationis not strong enough to establish a clear trend. This could be partially the result of theexperimental design used in this research. As shown on Figure 6.3 only a limited number ofmixes were studied with a low FAA value. If more mixes were included with a FAA of less than40, then the correlation would have probably been stronger.Comparison of Marshall and Superpave. As mentioned in Chapter 2, Habib (1998) studied thedifferences between Marshall and Superpave design methods for low-volume roads. Habibfound that values for asphalt content, VMA and VFA of the Superpave mix design were lower