Weeping Roads

[ The pictures on this page are copyright, and permission is not given, and will not be given for them to be reproduced  in any other publication or articles, visit some sites, see for yourself what is happening, and obtain your own photographs ]

Let me say emphatically right at the beginning I am not going to identify the site, contractor,  supplier or product because this problem is not specific to this site, the particular bituminous mixture or those involved.
I am personally aware of at least two other large international companies where I could show similar problems with "new" bituminous surfacing materials, and that is just in the smallish area in which I live and travel, and I refuse to believe it is only happening in my "patch". I am also told of similar situations observed by colleagues that I have not seen myself.
The only reason these pictures appear on this page is because I was in the right place at the right time to capture images that truly highlight the problem. This was two days after the heavy thundery rain storms we experienced recently during a period of very dry hot weather.
The conditions I describe means the road surface in general soon dries out leaving the areas of "weeping" clearly discernible. After a few days in dry summer weather they will be gone. 
But in the wetter colder days of winter the road surface will remain wet most of the time, and the "weeping" will still be occurring, but it will not be noticeable.
The common factor with all the sites that I know of is gradients, water is being taken into the voided matrix, flowing through the porous material, and then exiting under a head of water from above wherever it meets an impervious barrier, or in some cases a change in levels.  
I am going to make little further comment other than to say that in depth knowledge of bituminous materials, and their production, by all concerned could have prevented this happening, and a lot of money would have been saved by not having to instigate increased rates of spread of salt at increased frequencies during the winter maintenance period.
However, I will draw your attention to the considerable amount of drainage requirement specification that was stipulated when we were still laying Porous Asphalt to BS 4987, and the Specification for Highway Works, some of the new materials are no less porous than Porous Asphalt, but are used without similar drainage requirements.

I also think the laying contractor is very often being put in a very difficult situation not of his own making, and a good Materials Engineer / Road Pavement Engineer should be able to explain the meaning behind my various comments.

A selection of thumbnails to give you more information without slowing down the page loading time.

BS 594 and BS 4987
There has been new editions of BS 594 and BS 4987 published in August 2003, as these British Standards come in to force on the 1st. January 2004, it might be a good idea to arrange purchase of them soon. 
That is if you intended to continue to use generic bituminous materials.
I have said this many times, and I will say it again, the comprehensive use of these British  Standards means you should not go too far wrong in the specifying and use of bituminous mixtures for local authority road networks.
And I would like to see the availability of some of these materials re-introduced on to the motorway and trunk road network in England.    
The issue of these standards is coupled to the introduction of, 
BS EN 13043 : Aggregates for bituminous mixtures and surface treatments for roads and other paved areas
More information on this subject is available in the May 2003 and the August 2003 editions of the newsletter.
It is my opinion the large changes that are coming in the specifying of aggregates, and aggregate related materials, will not cause the problems anticipated, as long as we are aware of the forthcoming changes. As long as we educate ourselves as to the content and use of the new standards we will be able to specify material that for all intent and purpose will be the same as those we have always been using, and proven to be successful.
Most of the large quarrying companies are prepared to present training seminars to your staff on this subject free of charge, if you require them, providing you are prepared to sit through the sales pitch at the same time.
I have not seen any of them, but I am told some presentations are very good, and some not so good.
If you choose to go down this route I would suggest you obtain a recommendation from a trusted colleague and not just accept an unsolicited offer over the telephone.
It is likely the quality of the presentation will be down to the nature of the presenter, does he come from a technical background or a sales background.
Or, if you have one, you could get your Materials Engineer to give the presentation.

Motto of the Month
"Conscience is the inner voice that warns us someone might be looking"