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 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, by using a surface hardness probe, 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 spread binder.
According to site conditions, it will also be necessary to consider the Polished Stone Value (PSV) and Aggregate Abrasion Value (ABV) of the aggregate source, and also the possibility of the use of an enhanced, polymer modified, binder.
It is important to be aware that there has been changes in the specification of chipping sizes, that came in to effect in 2005, it may be that all people involved in surface dressing are not completely aware of the changes in chipping size that may occur with the introduction of,
BS EN 13043 : 2002 : Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas
and,
PD 6682-2 : 2003 : Aggregates - Part 2 : Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas - Guidance on the use of BS EN 13043
more information on this situation can be found in the Practical Guide to Surface Dressing, as this is purely a page of larger pictures showing the process of surface dressing.
