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Bituminous Road 09.10.2015

Date post: 06-Jan-2016
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BITUMINOUS ROAD CONSTRUCTION Sufficient bitumen to ensure a durable pavement. Sufficient strength to resist shear deformation under traffic at higher temperature. Sufficient air voids in the compacted bitumen to allow for additional compaction by traffic. Sufficient workability to permit easy placement without segregation. Sufficient resistance to avoid premature cracking due to repeated bending by traffic. Sufficient resistance at low temperature to prevent shrinkage cracks.OBJECTIVES OF BITUMINOUS MIX DESIGNRequirements of Bituminous mixesStability DurabilityFlexibility Skid resistance Workability Desirable properties

Coarse aggregate (retained on 2.36mm sieve) Fine aggregate (passing 2.36mm sieve but retained on 75m) Filler (passing 75m), may be cement. Binder: Bitumen etc.

CONSTITUENTS OF BITUMEN MIX

DEFINITIONSBinder: A material used to hold solid particles together, i.e. bitumen or tar. Bitumen: A heavy fraction from oil distillation (also occurs as part of natural asphalt). Tar: A viscous liquid obtained from distillation of coal or wood.Rarely used in construction currently in the UK. Asphalt: A mixture of bitumen and mineral filler.Note that Hot Rolled Asphalt is a road surfacing material. Mastic: An adhering asphalt which is placed with trowelling. Macadam: A road construction material with binder and coarse aggregate. Tarmacadam was the first road surfacing material.Bituminous concreteAsphaltic/Bituminous concrete consists of a mixture of aggregates continuously graded from maximum size , typically less than 25 mm, through the fine filler that is smaller than 0.075 mm. Sufficient bitumen is added to the mix so that the compacted mix is effectively impervious and will have acceptable dissipative and elastic properties.


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