Asphalt reinforcement and road maintenance using Geo-synthetics

Geocomposites are increasingly being used as a means of extending life of existing or old road surfaces across Europe. The system can be used in conjunction with a surface dressing technique for short to medium term benefits, in the reconstruction of existing roads following the milling / planning process to remove the top surface or in new construction where the benefits can be designed in to the project.

Many advantages follow on from the use of this technique :

reduction in reflective cracking and aids stress relief in the surface
an effective seal to prevent the penetration of water and oxygen to the lower levels of the construction
to strengthen the road and resist rutting
to extend the life cycle of the road surface and reduce maintenance costs
improves the bond between adjacent layers or between old and new surfaces
increases chemical resistance to road salt and other damaging products
can be recycled at the appropriate time

When to use the technique

The technique can employed at the initial design stage of a road leading to improved life cycle costing and extended design life for the construction.

The technique can be applied as a maintenance or repair method in conjunction with surface dressing or after planning has taken place to remove the wearing surface.

Cost effectiveness

The initial cost is low when measured against the long term benefits.

A cost of £5 to £8 per sq.m for the supply and installation of the product will extend the life of the road surface by many years.

Life cycle costing exercises show that the life of road surfaces can be extended by a factor of four.

Other considerations

Installation must be carried out by an experienced company whose methods are approved by the manufacturer of the geocomposite being proposed.

Planing / milling must be carried out to the required standard before the approved installer can proceed.

The surface to receive the treatment must be clean and free from dirt, dust or vegetation and thoroughly swept to ensure no loose material remains.

All ironwork must be protected with an approved spray or tape.

Any cracks exceeding 4mm wide or pot holes should be filled with a suitable asphalt or bitumen material.

A regulating course may be required if the surface is of poor quality.

Generally the bond coat used will be 160/220 pen grade straight run bitumen and must be applied at the rate of 1.1 litres per sq.m via a calibrated sprayer or otherwise as agreed.

The calibrated sprayer must be in good working order and should be certified showing that it has been tested within the last twelve months and conform to BS1707:1989 Hot Applied Binder Distributors for Road Surface Dressing.

The rate and accuracy of the distribution of the bond coat should be checked at the commencement of work by means of a carpet tile test in accordance with Bs EN 12272-1:2002.

Laying the geocomposite should be done with a purpose made applicator.

The selected geocomposite must comply with BS EN 1538 : 2008 .

This will lay the material under tension and will press the membrane into the bond coat.

No creases or wrinkles should be allowed.

Lapping must comply with meet the manufacturers and installers guidelines.

All operatives must be well trained and competent in the laying of the product and possess and minimum of an NVQ Level 2 Certificate.

Environmental considerations

The introduction of a geocomposite will extend the life of the road network and will hence reduce the overall carbon footprint of a project in it's overall life.

The technique is quick and does not delay any other associated trades.

The products are able to be recycled at the appropriate time and where appropriate the resultant planning may be reused.

Life expectancy

As stated the inclusion of a geocomposite will extend the life of the road surface.
The degree to which this is successful will depend on the overall design of the road construction and the use of an approved installer.

Summary

Across Europe this technology is widely accepted and acclaimed.