In March this year, following complaints from residents about the worn and damaged road surfaces at a few locations at the Kenber Hill estate in Blackhall Colliery, I asked the council’s highways department to inspect the roads for potholes and carry out remedial works where required. In response the council confirmed that the roads had been inspected and that they warranted micro-asphalt surfacing works which were completed a couple of weeks ago.
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| The entrance to Kenber Hill from the B1281 |
However, I was contacted again recently by residents concerned about the uneven and untidy appearance of the road surface at some locations. I raised this matter with the highways service on residents’ behalf and received a response confirming that the works are only partially completed at this stage and will be finalised as soon as the initial surface application ‘beds-in’. I’ve published the response here in full:
Thank you for your correspondence in regards to the Micro Asphalt surfacing in Hall Close, Blackhall Colliery.
To confirm I arranged for a DCC Contract Supervisor to assess the site and the report I have received is that the current condition of the surface is exactly as it should be at this stage of its life. However it was noted that there was a little bit of loose material on the surface and the contractor has been instructed to return and sweep the site asap.
To address the residents’ concerns this type of surfacing is an established, proven process and is used nationwide, it is also an extremely cost effective preventive highway surface maintenance treatment. The main benefit is that it seals the surface eliminating water penetration, which is known to be a major cause of potholes, therefore extending the life expectancy of the road by slowing the deterioration.
Micro Asphalt is applied at a depth of approximately 15mm, the application is made up with a mixture of water, polymer asphalt emulsion, aggregate and chemical additives. The material when first applied to the existing surface is in a fluent state, the hardening of the material occurs through the evaporation of the water with the chemical additives assisting in this process by allowing the surface to harden without relying on the sun or heat. Finally the overrunning of the surface by vehicles then aid in the bedding in of the material.
Micro Asphalt is a 3 stage process, the first stage is to try and establish the correct profile of the carriageway, this is achieved by applying a regulation course. The second stage is to then to apply the running surface, at this stage the surface will look un-finished with the texture of the material appearing a little untidy. These are normal characteristics of the process and the appearance of the surface will improve considerably once the surface has had time to settle down, this is addressed by the passing of traffic which helps with the embedment of the aggregate and in addition to this the site will also be swept to help clear any excess aggregate. The third stage is the adjustment of the ironwork, this procedure is as follows: Before the site is surfaced all ironwork within the carriageway is masked with tape, on completion the tape is removed unless the cover is very low and would create a hazard if the tape was removed at this stage. Once the surfacing has had time to bed-in a separate crew returns to the site who then uncover and reset all the ironwork to the new carriageway level.