Polymer-asphalt binders are compound materials based on traditional bitumen with block copolymer of SBS (styrene-butadiene-styrene) type. The brittleness temperature of traditional bitumen is ca. 15–18 degrees below zero and even light dynamic stress causes the roadbed slacking. For comparison, polymer-asphalt binders have an improved brittleness temperature of 30 degrees below zero. The use of polymer-asphalt binders increases the span between scheduled road overhaul from 2–4 up to 7–10 years. The use of such bitumen increases the overall construction cost of 1 km of road by less than 1% and completely pays off in 2.5 years of at operational phase.
The key polymer raw material supplier for new bitumen (thermoplastic elastomers) is SIBUR, the only producer of this polymer in Russia.
The existing practice of using traditional bitumen in road construction causes short life of the road bed. Consequently, state assigned means are used to overhaul old roads, not to build new ones. The use of polymer-asphalt binders for overhauling old roads allows overhauling them less frequently and using released funds for construction of new roads that could by-turn unload old roads and extend their life time.
The efficiency of polymer-asphalt binders is supported by world experience. The long-term monitoring of US road network conducted within the framework of the Strategic Highway Research Program showed that maintaining costs for the sections constructed with polymer-asphalt binders was 10–30% less than for the section built with traditional road bitumen.
Bitumen emulsions are microscopic particles of bitumen dispersed in water. The stability of the system is promoted by adding a special substance, the emulsifier. Depending on specific technological and operational characteristics of the binder material the emulsions can be based on bitumen of varying viscosity as well as with the addition of various supplements (solvents, surfactants, polymers) or without them.
Bitumen emulsions have a number of economic and technologic advantages:
- bitumen saving by 30 – 40 %;
- emulsions do not require heating before use reducing power and man-hour costs 1.5 times;
- the emulsion completely sticks to the roadbed;
- bitumen emulsions can be applied to wet surfaces that enables road works from early spring to late fall.
In USA and Europe, emulsions are used for decades. They have replaced obsolete technological operations of road-surface treatment with bitumen and constantly find new areas of application in road construction.