APPLICATION OF POLYETHYLENE AND STYRENE-BUTADIENE-STYRENE MODIFIERS FOR PRODUCTION OF ROAD POLYMER MODIFIED BITUMEN FROM NON-OXIDIZED HEAVY PETROLEUM PRODUCTS
One of the common ways to improve the quality of road bitumen is the modification of road binders with polymer additives. The main purpose of introducing polymer into bitumen is to expand its temperature range of operation. The polymer modifier increases bitumen viscosity, softening point, elasticity, and improves low-temperature characteristics. Most often, oxidized bitumen is considered as one of the main components of the resulting polymer modified bitumen (PMB). At the same time, technologies for the production of road bitumen based on unoxidized petroleum products are of particular interest, since this approach not only does not require a bitumen oxidation unit at the petroleum refinery, but also improves the stability of the binder against aging and compatibility with acidic mineral materials in the production of asphalt concrete. In these circumstances, it is very important to study the possibility of producing PMB based on non-oxidized high-viscosity petroleum products - vacuum residue or asphalts of vacuum residues solvent deasphalting. The main purpose of present study was determination of the possibility of obtaining road PMB, corresponding to the standards of GOST 33133-2014 for road bitumen of popular grades BND 50/70, BND 70/100 and BND 100/130 without the use of oxidation technology. The introduction of both individual bitumen modifiers (SBS modifier DST-30-01V, low-density polyethylene - LDPE) and their composition into the petroleum base has been studied. Possibility to compensate for the disadvantages of using one polymer modifier with the advantages of another in obtaining PMB with the use of composite additives was shown. It is shown that on the basis of high-viscosity vacuum residue and asphalts of propane deasphalting, which are unsuitable raw materials for the traditional technology of bitumen production by oxidation, it is possible to obtain a product that fully complies with the standards of GOST 33133-2014 for grades BND 50/70 and BND 100/130. The use of a composite polymer modifier made it possible to replace part of the expensive SBS copolymer in the PMB composition with a much cheaper LDPE. The elimination of the need to use an oxidized petroleum base and the introduction of any plasticizers makes it possible to produce such PMB at refineries that do not have a lubricant oil production unit and a bitumen oxidation unit.