Avaliação reológica de ligante asfáltico 50/70 modificado com polímero reativo e não reativo associado ao ácido polifosfórico.

Abstract

The addition of polymers to the asphalt binder can considerably improve its low, intermediate and high temperature rheological properties, increasing the resistance of the asphalt mixture to cracks of thermal origin, fatigue cracks and ruttings. Reactive polymers are characterized by a chemical reaction generated in the modification, improving the compatibility between polymer and asphalt binder. However, two limitations can be pointed out: the high initial cost and the risk of gelation, leading the binder to excessive stiffness making it unbalanced and infusible. These two limitations restrict the use of this polymer to small contents, therefore its isolated use is not desirable because of the effect of improving the performance of the binder being reduced. However, the addition of a catalyst can be adopted to optimize the reaction between asphaltic binder and reactive polymer, with Polyphosphoric Acid – PPA being the most commonly used. This research has the purpose of studying the combination of 1) Ethylene Methyl Acrylate and Glycidyl Methacrylate – EMA-GMA (reactive polymer) and 2) High Density Polyethylene – HDPE (Thermoplastic Polymer) with association of 3) PPA (catalyst) in the modification of a CAP 50/70 used as a basic binder by empirical rheological tests (penetration, softening point, elastic recovery and storage stability) and fundamental rheological tests (Rotational Viscosity – RV, Performance Grade – PG, Multiple Stress Creep Recovery – MSCR, Linear Amplitude Sweep – LAS and Master Curve) varying the contents of EMA-GMA and PPA with the objective of finding an optimum content which provides a high performance asphalt and thus to compare it with the base binder and a modified asphalt binder with SBS – Styrene-Butadiene-Styrene (55/75-E), which is the most commonly used modified binder in asphalt paving in Brazil. The results indicate the effectiveness of the modified binder with the proposed additives in improving properties such as stiffness and elasticity, providing high resistance to ruttings and fatigue cracking under high temperatures, thus being an excellent substitution alternative to SBS.