Wetfix, Adhesion Promoter and Anti Stripping in Hot Asphalt
According to develop heavy crude oil refining technology which causes quality reduction of VB (primary substance of bitumen production), bitumen price increases and quality reduces. This matter will cause troubles such as bitumen corrosion, weathering, oxidation, detaching from materials in asphalt. Therefore, using admixtures and promoters for bitumen quality betterment in hot asphalt plants has become necessary. Wetfix is one of Sweden Akzonobel company’s product and Iran has a 5-year experience of using it with a proper price, low consumption as a reducer of stripping event and detaching bitumen from material and increasing durability of asphalt surface. Cohesion of bitumen in the current position to materials in hot asphalt has 2 main reasons:
- Unsaturated compounds in bitumen which have slight cohesion
- Vulcanization of rock materials in dryer which causes promoting hot asphalt cohesion to material side. ( the same attitude of capillarity in very fine pores of rock material surface)
(Surface) materials contained charged particles while bitumen has almost no charged particles and or with ineffective pH (particle charge), this means that:
- Silica and quartz materials which negatively charged
- Calcareous and dolomitic materials which positively charged
Or a mixture of two types of materials to produce hot asphalt. Therefore, Wetfix will promote cohesion, positive and negative bonding through bitumen ionizing out and increasing hydrostatic pressure. This process will prevent from infiltration of water (reduction of water absorption), cause long persistency on the bitumen surface and reduce stripping (evaporation and sublimation cause detaching bitumen from surface). This product is presented in different proper types according to the kind of substance used. Wetfix is used in very few amount of 2-5kg per tonne and it causes no transformation on mixing process and asphalt cooking method. Wetfix will promote cohesion up to 95% (based on T283 test).