1

Understand limits of surfacing seal

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

Understand seal classification

2

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

3

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

4

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate SurfacingInfluencing factors:

Traffic volumes

Traffic loading Traffic actions

Gradient

Surface texture required

Maintenance capabilities

Construction techniques, skills, plant Environmental conditions (Noise, UV etc Quality of base (new seal)

Conditions/uniformity of existing surface (reseal) Texture of existing surface (reseal) Initial and life cycle costs

5

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate SurfacingTraffic : Equivalent light vehicles (elv) / lane / day

ELV = L + 40 H (1 heavy = 40 elv)

Construction techniques: Double seals (S2) are less sensitive and thus more forgiving than single seals (S1)

S1 requires good shoulder to shoulder contact

Lower aggregate layer is keyed in S2 Upper aggregate can be retained by fog spray S2 Increased voids in S2

Corrections to 2nd and/or 3rd spray applications possible in S2

6

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

7

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

8

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing

9

TRH 3 : Surface Seals for Rural and Urban Roads

Selection of Appropriate Surfacing