Agents enhancing compactability by means of changing the temperature susceptibility of a binder have been used in many countries. They enable the placement of a mixture at a lower temperature and make its compaction easier through the reduction of binder viscosity. Reduced binder viscosity enhances the compactability of a mixture, resulting in a decrease in the content of voids and an increase in the bulk density. In fact, it is this effect that can be seen in Figure 12.4, which shows example test results of a binder containing a Fischer-Tropsch (FT) wax. The application of an agent of this kind causes an increase in the bulk density of a mixture by about 15% in comparison with mixtures without this agent compacted at the same temperature. The presented mixtures contained the polymer modified binder PmB 45A (German designation).
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95 100 105 110 115 120 125 130 135 140 145 150 Marshall samples compaction temperature, °C FIGURE 12.4 Impact of FT wax on SMA compactability. (From Damm, K. W., Journal of Applied Asphalt Binder Technology, 2, 2002. With permission.) |
