TRH 3 : Surface Seals for Rural and Urban Roads
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TRH 3 : Surface Seals for Rural and Urban Roads Components. Aggregate Primary function:. Resistance to abrasion of base. Transfer of wheel load to pavement structure. Skid resistance. Structure for accommodating binder (water proofing). Protection of binder from UV.

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Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Aggregate Primary function:

  • Resistance to abrasion of base

  • Transfer of wheel load to pavement structure

  • Skid resistance

  • Structure for accommodating binder (water proofing)

  • Protection of binder from UV

Additional characteristics:

  • Light absorbing qualities to reduce glare

  • Differing texture or colour to define areas


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Aggregate : Factors affecting performance:

  • Shape

  • Nominal size

  • Grading

  • Hardness, durability, abrasion

  • Porosity / absorption

  • Cleanliness, dust content

  • Spread rate


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Aggregate : Factors affecting performance:

  • Shape – affects interlock and thus stability

  • Shape and size – affects void content / macro texture, binder application

  • Grading – affects interlock, contact area, noise

  • Strength – affects breakdown during construction and service

  • Wear – affects abrasion or polishing / micro texture (skid resistance)

  • Porosity – affects absorption of lighter fraction of binder (durability)

  • Cleanliness – affects adhesion


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Warning

Seal design method is based on strict standards w.r.t size, shape and grading. Changes to these standards could lead to current design approach being inappropriate with possible reduced performance.


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Binder function:

  • Waterproof pavement structure

  • Retain aggregate

Performance influenced by:

  • Adhesion properties

  • Cohesion properties


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Binder factors affecting seal performance:

  • Binder type and properties

  • Grade of binder

  • Spray rate

  • Viscosity at application

  • Stiffness, R & B ??


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Binder type:

Penetration grade

Cut-backSABS

Emulsion

Homogeneous modified (PMB)

Non-homogeneous modified (Bit-rubber)

Modified emulsions (various grades and binder content

Cutting back of binder – NOT generally recommended


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Factors influencing selection of binder:

  • Purpose of application i.e. tack coat, penetration spray etc.

  • Min. temp. at application and early life

  • Min. temp. during service life

  • Max. temp. during service life

  • Road geometry e.g. gradients, tight curves etc.

  • Traffic

  • Pavement deflection

  • Aggregate characteristics


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Properties of polymer modified binder for hot sealing applications


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Properties of polymer modified emulsions for surface seals


Aggregate primary function

TRH 3 : Surface Seals for Rural and Urban Roads

Components

Properties of bitumen-rubber for use in surface seals and asphalt