A runway is the most important part of any airport. Runways can be unpaved, gravel, asphalt or concrete. Unpaved runways cannot be operated in rainy weather, making the use of such facilities quite limited.
Considering the loads and the high pressures on the runway, asphalt mix or concrete is mostly used for modern runway construction.
The lenght of a runway made of high strength concrete is usually around 3 kilometers. Laying concrete is a complicated process. Concrete is applied in multiple layers, using concrete with different properties. This gives the runway the required strength and flexibility. Such runways can be used for high speed fighter jets and heavy transport or passenger aircraft.
A good example of asphalt laying is Miami aiport. Thanks to its geographical location and capacities, this aiport is one of the largest aiports in teh US and the largest hub for passengers travelling from Europe to Latin America. Despite the fact that most modern aiports have concrete runways, Miami airport is special. In this aiport, the runways are made of asphalt-concrete. The decision to use this material was made in teh 90s, because of the convinience and speed of asphalt-concrete runway repairs.
To make top layer, a mix of gravel (19mm max size) and polymer-modified bitumen was used. Using such binding is required to make the runway more resistant to rutting in hot weather.
Polymer-modified bitumen came into widespread use to due to the easy availability of the modifiers. But in each specific case the use of polymer required technical and economic reasoning. The binding used for Miami climate will likely not work well in other airports, and vice versa.
Bitumen are modified with polymers using the special USB-3 units made by GlobeCore. This product allows to produce 1 to 32 cubic meters of bitumen per hour and can be operated both outdoors and in well ventilated structures.
Modified bitumen made by the UVB-2 units can be used not only for runway construction, but also for repair and construction of highway asphalt top layer, waterproofing of buildings, soft roof construction etc.
