Evaluation of The Modification Efficiency of Bituminous Binders with SBS Polymer Based on Changes in Strain Energy in the Ductility Test

Road pavement layers in many cases are done of hot mix asphalt (HMA). It is mixture of mineral aggregate and asphalt binder. The content of the bituminous binder is not very significant (several percent). In fact, asphalt binder decides about every properties of hot mix asphalt in significant range. Traffic condition is still changing (traffic is growing and trucks are heavier). It is reason to find better solution to asphalt pavement and improve parameters asphalt binder. One of important attribute is sensitivity for temperature. Searching for a way to improve cohesion, viscosity and adhesion to mineral aggregate is one of the directions research. One of solution is use application of modifier. The most popular are polymers. Most frequently used copolymers to modify asphalt binder are thermoplastic elastomer styrene - butadiene - styrene (SBS). Thermoplastic polymers are used in practice, which soften upon heating and harden during cooling (reversible process), reminding in this respect the behaviour of asphalts. In article, authors have present tests results of modified asphalt binder by SBS polymer. Tests were made on two types of bitumen, one of them was distilled asphalt, second oxidised. Amount of modifier was variable and was from 0% to 6%. Results of test confirmed usefulness SBS polymer to modify asphalt. In every cases noticed increase penetration index (PI) and change structure of bitumen from sol-gel to typical gel. Effect of this is reduce thermal sensitivity. Resistance to changing of temperature is better. After tests and analyses, the authors stated that amount of polymer above 2% clearly changes asphalt parameters both hard and soft. (paper)