Are the old asphalts making a come back ?

8th February 2010 - 8:12 pm - by Mike Phillips

On my travels around the midlands recently I have come across three surfacing sites with paving machines, nothing unusual with that, apart from they have all been followed closely by a chipper. I guess the material they are laying are the age old 30% 14 HRA instead of the more modern thin surfacings. The question beccon's, are these making a come back ???

Replies: 3

Comments

Jack Roussell
11 Feb 2010 - 15:20

i know that i sound like a frog, but beleive me i am not, in fact far from it :)
it could'nt be anything else, as thin surfacing was developed by europeans who would'nt know what a bloody paver looks like never mind how to opperate one !!!!
good old english boys....show em how its done "properly"

Michael I Hardy
18 Feb 2010 - 17:03

Mike,
As one who is old enough to remember BS 1621,4987,1042 Tar spec (using Bitumen) & even Road Note 29 & was involved in one of the first Porous Ashpalt trials on the A38 Burton By-pass in the 80's - HRA (be it Recipe or Marshal Design) has always been the "Rolls Royce" of surfacing materials.
Yes there is always a need to develop new materials & binders for the ever changing demands of the road systems in our crowded Isle - however the rapid introduction of SMA/Thin surfacing materials a few years ago & the almost total abandonment of HRA was in my opinion progressed far too quickly.
Yes SMA & it's derivatives are a very useful, safe & cost effective form of road surfacing but the very fact they are, by design, open textured is part of the problem they create. They are failing on corners,roundabouts or even on straight but heavily trafficked areas such as motorways & this is in spite of the addition of harder & flexible binders, fibres etc.
Surely the answer is a combination of both these materials (& others) - HRA with it's durability & long life being used on the motorway lanes that need it, roundabouts & other heavy loaded areas with the thin surfacing materials used to give a smooth, safe & quiet ride on many major & trunk roads.
One final thought could the industry cope with a sudden demand for 20 & 14 mm precoats from Criggion, Bayston Hill,Craig y Hesk & those other "High" PSV quarries.

RMC Aggregates ...
6 Jan 2011 - 12:44

Hi all! be gentle with me on my first post.

BS594, BS4987 ah those were the days!

Could it be that the not so new SMA just isn't up to the UK weather and road conditions?

I've noticed on my travels that the new surfaces do tend to have a lot more standing water than HRA and pre-coats ever had. I've also seen a lot more cars facing the wrong way on the hard shoulder in various states of disrepair in the last few years.
One fuel spill and a large section needs replacing.

My own theory also is that in extreme cold the air voids don't drain as well as they should, the water freezes and expands causing a layer of black ice (only my thoughts I stress).

Has there been any research into this or am I talking pap?!