ON THE ROAD

Gone are the days of the jackhammer, the profiler, noise and landfill—road repairs are now becoming hi-tech.

The system, which recycles existing surfacing in-situ, is not only kinder to the environment, but is also proving to be cheaper, quicker and better than traditional methods of road patching and repair. The system uses infrared heat to heat up the asphalt on road surfaces, recycle and re-lay it in a matter of minutes.

Why the need for a new system?

In recent years, highway engineers have been put under increasing pressure to find ways of maintaining the country's roads against the backdrop of reduced budgets. Increased traffic flow and mounting concerns over the environment. The Government's attempts to reduce the amount of waste material ending up in landfill sites through the introduction of the landfill Tax has increased this pressure, and this year the Aggregates Tax, which aims to reduce the amount of new material being extracted from quarries, has also been introduced. The cost of traditional patching is increasing every year, the cost of disposal is up, purchase of fresh tarmac is up and labour and plant costs are also increasing - so something had to give. In the light of all these changes a new method of highway repair is timely, if not essential.

During periodic inspections the local Highways Inspector normally marks out the extent of the highway repairs in spray paint. The Highways Inspector's job is becoming increasingly more difficult as budgets are cut and the amount of repairs he would like to get done have to be governed by how far his budget will stretch. Increased traffic compounds the problem as surfaces are wearing out quicker and more maintenance is required. If left untreated the surface of any road will begin to deteriorate after just three to five years. The process of oxidation causes failure of the binder in the asphalt and together with the effects of weathering and increased traffic this quickly leads to crazing of the surface, the loss of aggregate and eventually full deterioration, resulting in potholes.

The old method

After inspection of the surface a gang of four or five men, in two large trucks, would turn up to set up the signing and guarding of the site in accordance with the traffic management manual. Once the site was safe they would then start up a floor saw to cut around the patch. Once this was done they would then start up a noisy compressor with even more noisy heavy-duty breakers to break out the old asphalt.

The use of breakers is very hard on the operatives and has resulted in the now common term 'white finger', the result of vibration, which can cause irreversible damage to the hands. The old asphalt is loaded into a lorry for disposal to a landfill site or sometimes to a recycling plant if there is one in operation nearby.

The new method

The infrared process can be used to repair the potholes much more quickly and efficiently. Firstly it is only a two or three man operation. After setting up working signs the Infrared equipment, which is easily towed behind a van or truck to site, is put to work within five minutes.

The system works by heating the road surface with infrared heat. The asphalt is gently heated to a depth of 50-75mm over a period of 8-10 minutes. Once the surface has reached a temperature between 130 and150ºC the unit is then pulled forward to begin heating the next patch. Whilst this happens the softened asphalt is raked around, and rejuvenation liquid, which is a water-based emulsion, is added to replenish the binder content of the old asphalt material. New material, kept in a small hot box of 2-6 tonnes capacity, is added if needed to top-up any depressions. The area is then re-raked, levelled and rolled leaving a hot welded patch all around.

The benefits

Environmental:

All of the existing tarmac surfacing is recycled;
Material sent to landfill has been reduced by 90%
Use of new material has been reduced by 85%;
The use of plant-using diesel engines has been reduced; one lorry is needed instead of two;
There is no need for noisy compressors and breakers. Road repairs in town centres can be carried out without disturbing residents;
The impact on the flow of traffic is dramatically reduced; only a small working area is needed, without the need for coning off large sections of the highway. Disruption is kept to a minimum.

Operational:

Much improved efficiency and output from smaller crews;
Easier and quicker to set up and get working, less down time;
Much safer and easier for operatives, reduced noise, jack hammers not required;
Reduced potential for damage to underground services, as no excavation is needed. Telephone lines and electrical supplies remain in service;
Any sized patch can be repaired; can be continuous without the need to cone off huge areas of the highway;
Leaves a heat sealed patch meaning less chance of water ingress and future damage.

Financial:

The cost of disposal is reduced by 90%
The cost of buying new material is reduced by 85%
The cost of running transport and plant is reduced by 30%
The cost of patching is reduced by 30%. The cost of highway repairs, inconvenience to road users, and disturbance to business and householders is reduced dramatically.

Quality

The quality of the repair using the infrared system is better. By introducing a heat sealed edge to the patch this prevents the ingress of moisture at a later date. The cause of many failures to patch repairs is the cold joint saw cut around the edge of the patch.

This allows the ingress of moisture, which during the winter months especially is susceptible to frost damage and softening of the road sub-base. The integrity of the highway surface is maintained with a more uniform surface without any weak points.

The use of the Infrared Restoration has enabled the reduction of the cost of patching repairs by almost 30%. Little or no waste material is going to landfill and the use of fresh asphalt has been reduced to just 25-30% of its original amount.

Any conscientious Highway Engineer cannot ignore the use of this technology. All county and local authorities should consider the use of this method of patching for the benefit of the taxpayer, road user and the environment.