WHAT IS SURFACE DRESSING?
Bitumen, usually in the form of an emulsion, is sprayed onto the road surface at an appropriate rate from the spray bar at the rear of a large tanker containing the bitumen emulsion. Chippings of an appropriate size are immediately applied to the bitumen by a large spreader, which usually tows behind it a lorry containing the chippings.
The bitumen part of the surface dressing as well as securing the chippings to the existing surface will seal the old road surface, thus preventing the ingress of water. Water if allowed to enter the road fabric, will cause severe damage to the strength/load carrying ability of the road and cause early road failure.
The chippings will restore texture to road surfaces that have become smooth with traffic wear. The correct texture on road surface is one of the most important aspects in preventing skidding accidents. Only premium quality aggregate should be used in surface dressing, i.e. aggregate that is known will not become smooth under trafficking.
Surface dressing will NOT add any strength to the road pavement, BUT it does keep an already strong road in a strong condition for longer by sealing water out.
THE FINISHED PRODUCT
The object of surface dressing is to create a stable mosaic of chippings securely attached to the road surface; this provides a comprehensive seal to prevent the ingress of water in to the road pavement, and a fresh hard wearing skid resistant surface.
This is achieved by spraying the correct amount of bitumen emulsion onto the road surface followed by the appropriate amount of the correct size of chippings according to the softness of the road surface. Once you have established the hardness of the road surface, and you know the amount and type of traffic, you need to consult TRL – Road Note 39 to design the appropriate dressing for the site.
This will mean determining the correct size of chipping and the correct rate of spray of binder. According to site conditions, it will also be necessary to consider the Polished Stone Value (PSV) and Aggregate Abrasion Value (AAV) of the aggregate source, and also the possibility of the use of an enhanced, polymer modified, binder.
SURFACE DRESSING BINDER APPLICATION
Spray Tanker Services offer a choice of binders from any UK supplier. The binders are delivered to site in our bitumen distributor spray tankers together with experienced drivers and operators. The drivers and operatives are all highly trained and will fit in with your own surface dressing operations.
BOND COAT \ TRACK COAT BINDER APPLICATION
Bond or Tack Coat is a cold or hot sprayed bitumen emulsion or polymer modified bitumen emulsion which provides a thin adhesive film between an existing road pavement and a new surfacing. It reduces the risk of slippage between the two layers and also allows the stresses to be uniformly distributed due to optimized contact between layers. Bond Coats are also used in patching applications where priming and waterproofing are required.
Bond Coats can be applied using conventional lorry mounted sprayers and should be spread as evenly as possible to achieve complete coverage of the existing surface. The selected rate of spread required will depend on the nature of the surface to be treated and should be carefully assessed. Bond Coats should always be used when overlaying cement concrete.
RETREAD ROAD RECYCLING
Retread road recycling has many benefits:
Reshapes Deformed Surfaces
Improves Riding Quality
Effective sealing to prevent water ingress
Low mobilization costs
Environmentally responsible process
Eliminates dumping of spoil
All existing bituminous materials used
Minimizes haulage movements
Low mobilization costs