Technologies for construction and maintenance of roads have been upgraded in recent years. These mainly include hot mix technologies involving use of modified binders and cold mix technologies involving use of cationic bitumen emulsions. In case of cement concrete roads, the technologies like use of high performance concrete and roller compacted concrete are gaining importance

The problem of maintenance of city roads has further magnified due to closure of hot mix plants in certain major cities. As such there is an urgent need to review available technologies and existing specifications. There is also need to explore adoption of new specifications and latest technologies, which are in practice for maintenance of city roads in an environment friendly manner in some countries abroad.

For strengthening and rehabilitation of structurally inadequate roads, generally bituminous macadam or dense bituminous macadam resurfacing is used as overlay. It is seen that temperature of mix goes down due to transportation of mix from long leads, which in turn results in unsatisfactory compaction and decline in the durability of the mix. As such it is important that non-polluting hot mix plants are installed at suitable locations. Use of insulated tippers for transportation of mix is also considered necessary.

The technology of hot mix plants has undergone improvement in recent years. The twin pack batch mix plants which can be assembled in short time, have been developed to produce mix close to site of application to reduce transport cost and drop in the temperature of mix. There are several international companies which produce such hot mix plants.

Recycling is another important technology of road upgradation. Insitu recycling does not merely renew the surface but also strengthens the crust of the road. It reduces maintenance cost in comparison to conventional methods of maintenance specially with reference to cost of materials. It is a fast process that enables early reopening of road to traffic. It also utilises the road materials once again. The technology could not make much headway due to non-availability of machinery and equipment in our country. There are global companies in the market which produce various types of recycling machines suitable to rehabilitate carriageway seamlessly and true to profile in one machine pass only. Such equipment can be used for off site or on-site recycling of milled material.

Recently some roads have been resurfaced by micro-surfacing and slurry seal technology. This is speedier, energy efficient, environment friendly and cost effective. Micro surfacing and slurry seal is made in specially designed equipment either truck mounted or continuous run. This machine carries a quantity of unmixed materials, which are proportioned and blended together through a continuous flow mixing chamber. The use of this technology ensures a smooth and consistently uniform mix.

Use of cement concrete overlays may be adopted for improvement of roads having drainage problems and heavy traffic conditions. Since the traffic and also the axle load are increasing with the passage of time, the pavement continuously needs rehabilitation and strengthening.

Concrete road construction including fibre reinforced concrete road construction is an appropriate technology for construction of durable road and overlay which has comparable life cycle cost vis-a-vis bituminous roads. The concrete road construction is done as a Fully Mechanised Construction and also as a Semi Mechanised and Labour Oriented Construction. The methodology has to be decided keeping in view the importance of the road.

The life cycle costs of different technologies and specifications need to be compared before deciding upon the choice of methodology for taking up road maintenance and rehabilitation.