In Europe, road binders (paving grade) according to EN 12591 and modified binders according to EN 14023 have been used in SMA mixtures. Normally, road binders of 50/70 and 70/100 are used; however softer 160/220 types have also been cited in the regulations for roads with light traffic. The properties of each type of paving grade binder are fully specified in EN 12591; Table 5.6 shows selected properties of 50/70, 70/100, and 160/220.
European Standard EN 14023 for polymer modified binder (PMB) is similar to EN 13043 for aggregates. It comprises two tables with PMB properties to be chosen by any CEN country. In this way, PMB with the same designation could vary significantly from one country to another. Table 5.7 provides examples of some PMBs specified for SMA.
Recently, a technology utilizing the simultaneous application of modified binder with a viscosity-reducing additive at high temperatures (e. g., F-T wax) has achieved great popularity.
|
TABLE 5.6 Selected Properties of Paving Grade Binders (Unmodified) according to EN 12591 paving binder grade
Note: R&B = Ring and Ball; RTFOT = Rolling Thin Film Oven Test. |
