Kazan scientists have found out how to make bitumen more resistant to high temperatures by studying the influence of polymer and petroleum components on its structure. Researchers from Kazan Federal University and A. E. Arbuzov Institute of Organic and Physical Chemistry discovered that adding 5% SBS polymer helps slow down the degradation of road binder when heated.
Bitumen binds crushed stone, sand, and mineral powder in asphalt concrete. During asphalt production, bitumen is heated, which causes light fractions to evaporate and changes the molecular structure of the material. Scientists studied these processes using synchronous thermal analysis, which simultaneously monitors mass loss and thermal effects.
It turned out that styrene-butadiene-styrene polymer forms a structure that retains light components and slows down their evaporation. More energy is required for such a binder to begin degrading. However, under extreme heating, the polymer structure also breaks down, after which degradation accelerates.
We found that a low-molecular-weight plasticizer makes molecules more mobile, the structure becomes 'loose,' and bitumen degrades more easily when heated.
The researchers also found that an increased content of asphaltenes — heavy petroleum components — reduces the thermal stability of polymer-modified binder, preventing the formation of a homogeneous polymer structure.
The obtained data will help in selecting the composition of road binders taking into account the temperature conditions of production and operation. However, this study concerns the material's resistance to heating: it does not yet prove that the developed composition has already demonstrated increased durability of finished asphalt on roads.