###### Abstract  
Recently, asphalt modifiers have increasingly gained attention for improving the mechanical and thermal characteristics of asphalt mixtures. As a result, innovative additives are being constantly developed to achieve this purpose. However, some modifiers can significantly impact the chemical and rheological properties of the asphalt binder. This paper investigates the rheological, spectroscopic, and chemical properties of asphalt binders modified with a bio-based phase change material (PCM) and phase change material mixed with glass powder (GPCM). Two binders were investigated, PG 58-28 and PG 70-28 polymer modified asphalt binder with 3% SBS. Two different percentages of GPCM (5% and 7%) were added to PG 58-28 and PG 70-28, and 5% PCM was added to PG 58-28. The results indicated that the PCMs effectively reduced the viscosity values of the asphalt binder. Moreover, testing the modified binders using differential scanning calorimetry (DSC) showed that the PCMs released the stored heat when the melting/freezing temperature was reached. However, adding glass powder with the PCMs negatively affected the thermal properties of PCMs in the asphalt mix. In addition, considerable changes in the stiffness of the binders modified with GPCM at an intermediate temperature were obtained when tested using DSR. Finally, the TGA results revealed that this specific type of PCM would not be suitable as a hot mix asphalt (HMA) modifier as its evaporation temperature is lower than the mixing temperature HMA. However, the use of PCM in warm mix asphalt (WMA) would be a more viable option. The results showed that the evaporation temperature for the PCMs was low; therefore, the PCMs cannot be used in HMA. In addition, modified binders with PCMs and GPCM showed lower viscosity compared to the control binder. The DSR rheological analysis showed that the control binder and 5%PCM, 5%GPCM, 7%GPCM, 5%GPCM, and 7%GPCM binders had similar overall properties. However, the addition of GPCM significantly decreases the stiffness at intermediate temperatures. s +
Footnote †: journal: Applied Sciences  
PCMs are thermal energy storage materials that can store or release a large amount of thermal energy during the phase change processes. Hence, PCMs are used in various applications in construction materials to improve their performance [3]. However, use of PCMs is argued to be significantly beneficial in improving the low-temperature performance of some materials, such as asphalt mixtures. It was reported by [PERSON] et al. (2010) that an asphalt mix containing PCM can control the asphalt mixture temperature ranges due to the change in the ambient temperature; this can delay the extreme temperature occurrence and shorten the extreme temperature duration. PCMs are classified based on their chemical compositions: inorganic PCMs, organic PCMs, and compounded PCMs (Eutectics) [4]. Limited studies were conducted to investigate the use of PCMs in asphalt mixtures, and these studies adopted different methods of mixture preparation. These mixtures were prepared using direct/indirect blending or the sol-gel method [5]. Ref. [6] reported that the direct blending method led to a leakage of the PCMs from the asphalt binders. As a result, there was a concern about the durability of the asphalt pavement modified with PCMs. Another study was conducted by [7] using the direct immersion method, which involved the immersing of a porous supporting material directly into the PCM liquid to form composite phase change materials (CPCMs). The study was performed by preparing different asphalt mixtures with different composite PCM dosages (0%, 5%, 10%, and 20%) that were tested for high-temperature stability, low-temperature crack resistance, and resistance to water damage. It was concluded that using CPCMs can reduce the effect of PCMs on the saturate, aromatic, resin, and asphaltene (SARA) contents of the asphalt binder. Moreover, CPCMs solved the leakage problems resulting from adding PCMs to the asphalt mix during the high-temperature mixing process. Ref.