The KGO-III (Viman et al., 2004) method has been experimentally applied in Sweden since 2002. It consists of changing the order of batching and mixing the constituents in a batch plant. The suggested KGO-III mixing order is as follows:
FIGuRE 9.5 One sequence of batching SMA constituents into a pugmill using a loose form of stabilizer. Notice that the times depend on the type of pugmill. (From Graf, K., Splittmastixasphalt — Anwendung und Bewahrung. Rettenmaier Seminar eSeMA’06. Zakopane [Poland], 2006. With permission.)
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
 |
FIGURE 9.6 Another sequence of batching SMA constituents into a pugmill using a loose form of stabilizer. Notice that the times depend on the type of pugmill. (From Schunemann, M., Faserqualitat. Eine wesentliche Voraussetzung zum Herstellen von qualitatsgerechten Asphaltbefestigungen. Rettenmaier Seminar eSeMA’07, Zakopane [Poland], 2007.)
• Stage 1—mixing binder with an aggregate larger than 4 mm
• Stage 2—adding filler only to dissolve it in the mixture
• Stage 3—adding fine fractions (0.063-4 mm)
Changing the order of batching and mixing are aimed at achieving a thicker binder film on the coarse aggregate. As we know, the smallest grains of aggregate are the first to be coated with binder, in a way capturing the binder and interfering with the creation of thick binder films on the coarse aggregate. Therefore the first stage of the KGO-III approach is intended to coat the bigger grains before the smaller ones.
According to Viman et al. (2004), by employing this approach, about 0.5% less binder may be used in comparison with a typical mixture. It has also been shown that the production temperature of the mixture can be reduced by approximately 30°C. Thus not only can the manufacturer benefit from savings in binder and energy costs, but the process is also favorable for the environment due to lower air pollution (e. g., less odors, fumes, and heat). Six different plants and manufacturers have produced in total 500,000 tons of the mixture according to KGO-III since 1998.
