The use of bitumen emulsion has several benefits compared to regular bitumen binding materials:
- the viscosity of bitumen emulsions at room temperature is several times less than that of straight bitumen, facilitating easy permeation even small pores of the treated surface;
- emulsion higher adhesion to various surfaces, making it possible to create stronger road layers;
- organic and mineral mix can be mixed in lower temperatures and in higher humidity due to better adhesion between the thin bitumen film with the rough surface of the mineral;
- the temperature of heating the mineral material is lower, so fuel and energy can be saved in the process of asphalt mix production if emulsion is used: the temperature is 20-40 °С lower than the regular mixing temperature. This translated into 30-40% economy compared to the traditional process;
- the precision of metering the binding material and its distribution in thinner layers due to reduced viscosity decreases binding consumption;
- atmospheric emissions are reduced due to the absence of organic solvents and low production process temperatures.
Emulsion are taking the place of traditional bitumen materials in road construction. Literature analysis demonstrates that the current applications of bitumen emulsions in road construction are as follows:
- Tac coats. A fast breaking water bitumen emulsion with 50% bitumen is used. The emulsion is sprayed evenly across prepared and cleaned road surface in the amount of 0.2-0.3 liters per square meter. After emulsion breaks, the road is covered with a uniform thin layer of bitumen for adhesion of inert materials.
- Ground reinforcement with slow breaking anionic water bitumen emulsions increases the strength of the road base. Bitumen concentration and type depend on the humidity of the ground.
- Slurry treatment is used for repairs and maintenance, such as preventing oxidation of bitumen, repair of surface cracks etc. A 3-6 mm layer of slurry is applied using medium and slow breaking emulsions with 60-65% bitumen content.
- Dust consolidation with bitumen emulsion is performed on dirt roads to prevent excessive formation of dust. Slow breaking emulsions with 60% bitumen is used in this process. Emulsion consumption rate depends on the road surface and varies in the range of 0.5 – 2.0 liters per square meter.
- Cold recycling is a highly efficient process, approximately 20% less expensive than traditional repairs. Cold recycling reduces the duration of road repairs by 40-50%. Medium and slow breaking emulsions with 60-65% bitumen are used for this purpose. The process implies preparation: cutting and stone material with binding materials on site.
- Patch repairs by filling openings with fine ballast treated with water bitumen emulsion. The material is placed at a high rate by compressed air feed, which also improves compaction. Fast breaking cationic or anionic water bitumen emulsions are used for this purpose, with bitumen content of 65-70%.
- Cold asphalt mixes are mixed water bitumen emulsion and mineral materials of the required composition. This process required controlled break emulsions. Such surfaces are self-balancing and are highly stable. Due to increased deformation and water resistance, as well as good adhesion, the costs of road repairs are reduced by 38%. There is a variation of this process, known as microsurfacing, which involves application of asphalt mix in a thicker layer. This process can correct small deformations and prevents rutting due to laying several layers of the material.
- Rough surface treatment is performed on top of the primary coat by applying a thin film with later filling by ballast of the required composition and shape and subsequent compacting of the layer.
It should be added that bitumen emulsion are also applied outside of road construction. For instance, bitumen emulsions are used in construction for waterproofing of concrete structures and the ground under buildings by impregnation. Bitumen emulsions are also widely used in the production of thermal and electrical insulation materials.
