Micro resurfacing - video transcript
[Caption] Micro resurfacing - A Kent County Council video guide.
Russell Boorman, a resurfacing team leader, explains the process of micro resurfacing.
Russell: "Kent has one of the largest and busiest road networks in the country. We look after more than 5,000 miles of roads and 4,000 miles of pavements. We work hard to ensure that every penny of funding that we have available for road maintenance is spent wisely. To do this, it is vital that we choose the right treatment in the right place at the right time.
Each year we survey our roads to assess their condition. This enables us to produce annual programmes of maintenance schemes. We have a number of maintenance techniques available to us including major resurfacing and surface treatments.
Major resurfacing usually involves planing off the top layers of the road surface and replacing them with new hot mix asphalt. This is an expensive process, which can be very disruptive. It is used on those roads showing pronounced signs of deterioration, such as extensive cracking and rutting.
Rather than replace the existing road surface, we can treat it to prolong its life. Surface treatment techniques used in Kent include surface dressing and micro asphalt. These are preventative maintenance techniques and are used on those roads that are showing very early signs of deterioration. They effectively stop the deterioration and prevent the road from reaching the point where an expensive major resurfacing scheme is required.
Two weeks before we are due to start the treatment, we will put up advanced warning signs at each end of the street, and deliver an information letter to each property and business on the route of the works. This is also sent to the emergency services, bus companies, local parish councils and local councillors.
Keep an eye out for a letter like this being hand delivered through your letterbox. This letter will tell you when we are planning on being there, how long it will take and whether we will need to close the road. If so, the diversion route will be given. We will always allow access to properties but we just ask that you are patient since the machinery we use is large and may take a few minutes to move.
It is vitally important that residents and businesses move their vehicles on the morning of the planned treatment. The site operatives lose valuable time trying to locate the owners of vehicles before work can start. Sometimes, the only option is to ask the Police for assistance to track down owners, which diverts them away from valuable work in the community so is only called upon as a last resort. Sometimes, even this fails and it is necessary to leave an untreated space on the road.
It is very disappointing when this happens as it means the work is incomplete and another visit has to be scheduled at a later date to try to complete it.
Once the road is clear of vehicles, the site operatives will cover any gullies and other ironwork with protective tape and mark their position with degradable spray paint on the kerb. Then the laying of the new treatment begins.
Micro asphalt is a superior form of slurry surfacing, which consists of a mixture of aggregates, cement, additives, fibres and bitumen emulsion. These components are mixed in a specialised lorry and then applied cold, in fluid form to the road surface in two 8mm thick layers. These layers seal the surface to prevent water penetration, restore texture and improve skid resistance.
The first layer is rolled in order to achieve a compact surface on which to lay the top layer. The top layer is not rolled as we want the stones to remain proud of the bitumen whilst it cures to give texture to the new surface; this influences skid resistance and durability. The action of a roller would push the stones deep into the bitumen, which is why we rely on the movement of vehicles, which are much lighter, to aid the embedment of the stones.
Micro asphalt is quick to apply, which means less disruption to road users, residents, local businesses and the emergency services. And because it is cold applied, has a low carbon footprint.
The finished surface looks quite dark in colour, coarse, uneven and rough immediately after laying. This is perfectly normal. As you can see the stones are standing proud just as we need them to be. It is fair to say that aesthetically micro asphalt looks pretty untidy when it is first laid but the good news is that this appearance doesn’t last long as once the material starts to bed in, usually around 4 to 6 weeks after laying, it takes on the smoother and more uniform appearance that we are used to seeing on our roads.
Once the treatment has been applied, we will re-paint the road markings and adjust the level of the ironworks (road drain covers, manhole covers, etc) if necessary, to suit the new surface. Generally, this all happens within 7 days of laying the new surface and the site operatives will puncture the protective tape to allow any surface rainwater to escape before the gully covers are adjusted.
Micro asphalt has been applied successfully over many kilometres across Kent. It offers very good value for money and helps our funding to go further, to ensure that every pound of taxpayers’ money is spent wisely. Without it, the amount of roads we would be able to maintain in Kent would be limited.
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