The second way to counteract the draindown phenomena is to use a binder viscosity promoter. The most common agents used to be polymers, either plastomers or elastomers. Test results show, however, that the efficiency of polymers is not as good as that of fibers. Currently in many countries, regardless of the type of applied binder (modified or paving grade), fiber stabilizers are required. Binder modified with special materials may be considered, except for polymers directly metered into a pugmill at an asphalt plant. Polymer stabilizers also have a higher viscosity over the preferred range of production temperatures. This is when the use of a classic stabilizer is indispensable because, as a number of failed attempts have shown, modified binder itself does not protect an SMA mix from segregation.
The application of viscosity promoters acting at temperatures of 100-160°C may also increase problems with compaction on site because an SMA mix is hard to compact, even without an additive that stiffens the binder and makes compacting the mix even more difficult. This fact should not be forgotten when choosing a stabilizer to use.
