Environmentally Tuning Asphalt Pavements Using Microencapsulated Phase Change Materials

Environmental conditions are considered an important factor influencing asphalt pavement performance. The addition of modifiers, both to the asphalt binder and the asphalt mixture, has attracted considerable attention in potentially alleviating environmentally induced pavement performance issues. Although many solutions have been developed, and some deployed, many asphalt pavements continue to fail prematurely because of environmental loading. The research reported here investigates the inclusion of microencapsulated phase change material (mu PCM) in asphalt binders and mixtures to help reduce environmental damage to asphalt pavements. The mu PCM particles are formulated to absorb and release thermal energy as the particles liquify and solidify, depending on pavement temperature. As a result, mu PCM can provide asphalt pavements with thermal energy storage capacities to reduce the impacts of drastic ambient temperature scenarios and minimize the appearance of critical temperatures within the pavement structure. By modifying asphalt pavement materials with mu PCM, it may be possible to "tune" the pavement to the environment. Through rheology, differential scanning calorimetry, thermal cycling, and dynamic modulus testing, this work attempts to capture the mu PCM effect and link the behavior between mu PCM modified asphalt binders and mixtures. This study identifies a novel approach to determine when the mu PCM effect occurs using rheological measurements. Additionally, the thermal and mechanical performances of mu PCM modified asphalt mixtures are evaluated. An asphalt mixture design method is demonstrated to systematically incorporate a substantial portion of mu PCM particles in a reference mixture. The findings extend the thermomechanical understanding of mu PCM modified asphalt binders and mixtures.