Headache of concrete roads
One of the biggest headaches faced by highway engineers and technicians must be what treatment to use on concrete roads. I certainly know from local residents who’ve contacted me about what they class as defects on these residential roads that by and large it is only that of tarmac that was laid to make them more aesthetically pleasing to the eye that is starting to wear. That’s not to say that even concrete slab section roads can’t have defects and indeed they do and I suppose like the multi storey car parks built in the 60’s that they too suffer from concrete cancer.
So, after a lot of deliberations and work carried by the Materials Lab on a way forward, it now looks as though we’re ready to take forward a trial which if successful can be rolled out across the County.
The first part of the three-stage process is to carry out joint sealing, this is then followed by either Dragon Patcher or another Road Mender Solution and then finally Micro-Asphalt which is a quick, efficient and economic method of preventative maintenance. It is a mixture of polymer modified bitumen emulsion, small aggregate and cement laid using specialist machinery and which will improve the road surface and extend the life of the road.
Interestingly immediately before the Micro Asphalt treatment the road will be cleaned and all the ironwork, (covers, gullies etc), will be ‘masked’ to protect them from the Micro Asphalt material.
The Micro Asphalt process is a two-phase process. First, a regulating layer of material is applied. This improves the surface profile of the road. This is followed by a second layer which gives the final surface. Both layers are usually applied on the same day, to a thickness of approximately 14mm.
The Micro Asphalt layers typically take between 15 and 30 mins to dry. This is dependent upon temperature and humidity. When the material is first laid it is a brown colour. the colour changes to grey/black as the material dries.
Once the final layer of Micro Asphalt has dried, the masking material is removed from the iron work. However, where the process extends beyond a single day then the iron work will remain covered, but provision will be made for water to be able to enter gullies in case of rain. All Fire Hydrants will be uncovered in case of emergency.
Following the completion of the works there will be some chipping loss. Warning signs and an advisory speed limit will be put in place and roads will be swept as required to remove loose material. Traffic movement assists with the embedment of the newly laid material. The new surface can generally be driven on within 30 minutes of completion of application.
A few days after the Micro Asphalt has been laid the contractors will return to site and raise any low ironworks.
Lining at junctions etc will be replaced up to a few weeks after the Micro Asphalt has been laid to allow for sufficient embedment. Once again, this work is weather dependant. Finally, the completed work is jointly inspected by a representative of the County Council and the Contractor.