6.3.2 Double/double Seals
Double/double seals are strong robust seals by virtue of the mechanical interlock of the large and smaller aggregates and are not as reliant on the binder as a single/single seal to cope with high traffic stress. Binder factors for double/double seals (Table 6.5) are thus reduced compared to those used for single/single seals.
|Treatment type||Binder||Binder factor(1)|
|Conventional seal||C170, C240, C320||1.0|
|Unmodified emulsion seal||Conventional emulsion (60%)||1.0|
|High bitumen content emulsion (≥ 67%)||1.1|
|Modified emulsion seal||User binder factors below for the PMB that has been emulsified|
|High stress seal (HSS2)||S10E, S15E, S35E||1.0|
|S20E, S45R, S15RF||1.1|
|Extreme stress seal (XSS)||S20E||1.1|
|Strain alleviating membrane (SAM)||S10E, S15E, S35E, S20E||1.1|
- Under very heavy traffic conditions with high percentages of heavy vehicles these factors may be reduced by 0.1 but should not reduce the binder factor to less than 1.0.