COMPOSITE MODIFICATOR OF ASPHALT-CONCRETE OBTAINED BY THE METHOD OF HIGH-TEMPERATURE SHEAR-INDUCED GRINDING OF CRUMB RUBBER AND SBS THERMOELASTOPLAST

Abstract

The mandatory requirement for creating high-quality asphalt concrete is the modification of the bituminous binder. Either polymers, typically SBS, or crushed vulcanizates are usually used as modifiers. Using the polymer modifier has a number of disadvantages: the poor compatibility of polymers with bitumen, the stratification of the modified binder during transportation and storage, the coalescence of the dispersed phase particles at the coating laying temperatures. The use of crushed vulcanizate as a modifier is limited due to the complexity of obtaining a particle with a micro-size and complex surface organization. By now a binary mixed powder "Polyepor-RP" based on rubber crumb and butadiene-styrene thermoplastic elastomer has been developed and obtained. It combines the advantages of both types of initial constituents and eliminates their shortcomings. The hybrid modifier is obtained by the method of high-temperature shear grinding. In addition, thanks to the use of modern rotary dispersants, the resulting hybrid modifier can be introduced into the asphalt mixture by uniformly loading it into the mixer at the closing stage of mixing, bypassing the long and energy-consuming stage of preparing the modified bituminous binder. The paper describes the comparative analysis of the rheological properties of four types of asphalt binders in accordance with the American testing system "SuperРave": unmodified bitumen of BND 60/90 grade; polymer-bitumen binder; bitumen modified with active rubber powder brand "Polyepor-A" and active binary powder brand "Polyepor-RP". It is established that the introduction of modifiers "Polyepor-A" and "Polyepor-RP" increases the resistance of asphalt pavement to the formation of ruts and increases the resistance to fatigue cracking. The introduction of the butadiene-styrene thermoplastic elastomer into bitumen has a positive effect only on the resistance to rutting. Using a hybrid modifier it is possible to obtain a rubberpolymer binder characterized by higher stability, resistant to delamination and phase separation, which will increase the durability of coatings