New Pages

I have created a few new pages even though it is the summer here and I spend less time at the computer, this is probably because they are pages consisting mainly of photographs and take less time to prepare, not that they are any less useful, in fact some of you prefer them.  
You will find these new pages on the "Fast Loading Photographs" menu, I have tried to keep all the pages on this menu to about one minute download time, according to your modem speed and internet connection. 

Evolved Roads

This item is probably only relevant to U.K. roads, but possibly Europe as well, where roads have evolved over the centuries and will have included a period where they had to withstand trafficking from the iron clad wheels of carts and carriages. 

The photographs above go a long way to illustrating my point about the inherent road pavement strength of some evolved roads, and the fact that this strength must be recognised and allowed for in road pavement refurbishment and overlay.
The failure to recognise this strength and incorporate it in the new work will not only incur increased expense but could also introduce fresh problems if a total road pavement reconstruction is decided upon.
When total reconstruction is decided upon in urban environments this very often has to be undertaken as a number of small areas of construction so that traffic will still have access to the road under reconstruction and other roads and premises leading from the site. This in turn can often mean there has to be many vertical joints included in the construction of the road. 
Every one of these joints will be a potential failure of the road pavement because it is practically impossible, even with the best of intentions,  to fully compact the areas around the joint between different sections of construction.

It has to be a considered option to "plane off"  the failed road pavement layers in one operation, leaving the large aggregate pitchings in as undisturbed manner as possible. The removed material to be replaced  with "premium" base (roadbase), binder course (basecourse) and surface course (wearing course). This option allows  material to be removed and replaced quickly with only a brief road closure, usually a Sunday, and few if any poorly compacted joints.

My personal preferred material options in these situations are Hot Rolled Asphalts, wearing courses and basecourses, this is because they have stiffish binders (50pen.) and high binder contents relative to coated macadams.
Each site has to be considered on merit after good site investigation that includes a number of decent size trial holes to be able to obtain a clear picture of the nature of the road pavement construction.
But it has to be noted well seated "pitchings" (known by other names in various parts of the country) provide an extremely strong load distributing layer as a foundation to subsequent road pavement layers. 
One also has to remember that 95% of roads in this country are NOT motorways or trunk roads, and a large portion of the 95% will be evolved roads carrying only moderate amounts of mixed traffic.
Although over designing these lesser roads may be one option to providing a long road pavement life it is probably not the best use of inadequate budgets, and not what I regard as true highways maintenance engineering.
To those of you out there who already employ this procedure I apologise, but there are a large number of young engineers and technicians, and those more familiar with "green field" road construction, who are lacking experience in maintaining road pavements of a more unorthodox nature, these notes are so that they might ask a few more questions before deciding on a course of action.

Recycling Bituminous Materials

The Aggregate Information Service has just published a number of new digests on various subjects relating to recycling in road pavement construction and maintenance.
These are in addition to the considerable number of excellent digests already present on the site.
Copies of these digests can be obtained from their website in .pdf format, well I am sure they will be able to be downloaded when one or two gremlins have been sorted out that is preventing the download of particular digests, especially "Digest 68 : Road Maintenance, Small Scale Road and Footway Maintenance Using In-Situ Recycling Technologies", which I am keen to get a look at, hopefully this will be sorted by the time you access them.
The Aggregate Information Service (AIS) is operated by Viridis, the sustainability and waste management research arm of the Transport Research Foundation.
AIS is funded by the RMC Environment Fund under the land fill tax credit scheme, with third party funding from the Department for Transport, Local Government and the Regions.

It is my opinion that if a bunch of people sat down to create a user friendly totally recyclable road making material they would be hard pushed to create a product better than bituminous material, i.e. a mixture of good quality aggregate and bitumen.
Providing this material, of whatever particular type, is treated with the care that comes from knowledge of the material, ( do not over heat it in the recycling process ) it is able to be recycled many times.
However, there is a very important point to make, which is that we are talking about bitumen based bituminous materials, although the word tarmac is used quite commonly to describe bituminous materials there has been very little tar used in general road making in the thirty years I have been involved in the industry, for the simple reason that as soon as natural gas replaced "town gas" there was not the large source of tar available to be used as a cheap bituminous binder. 
(A bit of history for all the "youngsters".)
I mention this because tar has a few health problems associated with it which bitumen does not have. I would regard it as quite unlikely to come across tar based materials when recycling any bituminous materials that is less than thirty years old, which is likely to be the the bulk of material you will be dealing with. 
If this is not the situation in the area you work it is something you must be aware of and make provision for.

If you wish to know a little more about recycling bituminous materials may I suggest you visit the page on this website that offers some relevant information, and links to other sites involved in various recycling processes.  

Motto of the Month

"You can fool some of the people all the time, and all of the people some of the time, but you cannot fool all of the people all of the time"