ASPHALT FOR SURFACING AND GENERAL REQUIREMENTS:

The required composition of asphalt for surface courses and binder courses depends substantially on type of traffic load and the construction class. Specifies normal aggregate sizes for asphalt binder courses and surfaces courses, as well as for various types of mixtures, depending on traffic load.

               The permissible laying thickness for the relatively thin surface courses depends mainly on the particle size of the mixer independently from the standardised thickness according to the design. The stability of asphalt surfacing (asphalt binder courses and surface courses) made of rolled asphalt can be improved by favourable adjustment of the proportions of chippings and crushed sand as well as the use of high-grade aggregates with higher proportion of crushed surfaces, whereas the durability can be enhanced by a perfect adaptation of the binder content to the air void content.

               Hard binder or low binder contents, as may be considered for high traffic loads, contribute to the potential of crakking.The stability and durability of gussasphalt depends to great extent on the interaction between binder and filler and their homogeneous distribution in chipping/sand particle skeleton. For the polishing resistance of high-grade chippings in surface courses and spreading of chippings. The deformation resistance of asphalt surface courses is substantially influenced by the temperature of the mixture and, during laying, by its cooling and reheating. During mixing and laying certain maximum and minimum temperatures must therefore be complied with dependence of binder grade and type of mixture.

NATURAL ASPHALT AND MODIFIED ASPHALT:

NATURAL ASPHALT-Natural asphalt is added to gussasphalt, stone mastic asphalt and mortar enriched asphalt concrete among others, e.g. as natural Trinidad-asphalt. These additives can enhances the stability of surface course or binder course and have a positive effect on processing and compaction.

ELASTOMERE MODIFIED ASPHALT:

The mechanical and elastic properties of rolled asphalts can be modified by adding caoutchouc or rubber. This improvement is particularly related to elasticity, adhesion strength, ageing resistance against water and weather influences as well as fatigue resistance.

POLYMER MODIFIED ASPHALT:

The use of polymer modified bitumen or the addition of polymers enhance the adhesive properties, the stability and elasticity and, when increasing the binder content, even the ageing resistance and durability against the influence of water and weather.