EXTENDING THE LIFE SPAN OF ROAD PAVEMENTS
IMPROVING SURFACE CHARACTERISTICS
Due to the adverse effects of traffic and weather conditions, it is advisable to install some form of protection to the wearing course of pavements at regular intervals. Surface coatings belong to conserving road maintenance technologies, i.e. they serve to “regenerate” the top layer of pavement structures, and to extend their life cycle. Such technologies are used when the load bearing of the given pavement is still sufficient, but the wearing course is flaying, cracking, and is losing its roughness.
LESS FREQUENT PAVEMENT RENOVATIONS
Surface coatings form a watertight layer on top of the pavement – consequently, they have a favourable effect on the entire pavement structure. By applying surface coatings in due time, the periods between pavement renovations can be extended significantly.
Surface coatings are thin layers applied to the wearing course, and the bituminous binder is installed onto the surface by means of spraying. This is followed by the sprinkling of aggregates to be installed with pneumatic rollers. Warm, sunny periods are the most ideal for applying surface coatings, which means that such works are generally performed from the spring to the autumn.
The installation of surface coatings calls for considerable experience and thoroughness. The proper quantities of binder and aggregates is crucial, and the even particle size distribution of the latter is also key. If excess quantities of binder are sprayed onto the surface, roads might become slippery, while the insufficient quantity of binder will cause aggregates to wash off from the surface.
- Single-layer surface coating: installed with a single spraying of binder followed by one-time application of aggregates.
- Single-layer surface coating with dual aggregates: installed with a single spraying of binder followed by two phases of aggregate application (e.g. KZ8/11, KZ2/4).
- Dual-layer surface coating: installed with two binder spraying phases followed by two phases of aggregate application.
- Dual-layer, inverted surface coating: installed with two binder spraying phases followed by two phases of aggregate application, but the aggregate with the smaller particle size is applied in the bottom layer.