Temperature is significantly influencing the behaviour of asphalt road surfaces. In case of cooling, asphalt pavements become stiffer eventually reaching a brittle state at which thermal cracking may occur. Phase change materials (PCM) respond to the environmental changes by actively altering their own properties by absorbing, storing, or releasing heat without changing their own temperature. Nevertheless, the application of phase change materials in thermoplastic materials, such as asphalt, has drawn attention only recently. The current study aims with an innovative approach for buffering and controlling extreme low temperatures in asphalt road surfaces by incorporating PCM as an additive for storing heat energy in a latent form. However, the results showed that the addition of Tetradecane as raw PCM material into the bitumen 10/20, 70/100 and 160/220 drastically increased penetration and decreased the conventional characteristics such as softening temperature as well as the complex modulus. The results of this study reveal that the direct interaction of Tetradecane with bitumen significantly affects the rheological properties of bitumen without storing heat energy in a latent form. Therefore, the choice of a suitable PCM and its incorporation in bitumen (e.g. microencapsulation, shape stabilisation) and possible leakage of protected PCM due to breakage of shell is very important in the context of bitumen modification.

Latent heat storage systems are gaining the attention of researchers as possible substitutes to conventional sensible heat storage systems due to their compactness and their ability to absorb and release heat almost isothermally. Among the Phase Change Materials (PCM) for energy storage studied so far, esters are believed to show promising properties. In particular, a broad range of melting temperatures, little to no supercooling, low corrosivity, chemical and thermal stability, and high enthalpies of fusion are reported. Many esters have the advantage of being bio-based and biodegradable, making them more sustainable in comparison to other popular PCM. Still, a clear lack of experimental data exists in regards to this class. In the present study, esters derived from saturated fatty carboxylic acids (myristic, palmitic, stearic, behenic), coupled with primary linear alcohols of different length (methanol, 1-decanol) were synthesized through Fischer esterification and their properties were investigated. Purities higher than 89% were obtained for all cases as proven by gas chromatography coupled with mass spectroscopy and nuclear magnetic resonance analysis. Additionally, the esters’ formation and reaction kinetics were characterized by attenuated total reflectance infrared spectroscopy. The esters produced showed to possess relatively high enthalpies of fusion above 190 J/g and thermal stability over three repeated cycles with differential scanning calorimetry. The melting points measured ranged between 20 °C and 50 °C, therefore proving to be interesting candidates for low-medium temperature applications such as heating and cooling in buildings. A correlation could be observed between the chemical structure and melting point of the produced esters. Additionally, thermogravimetric analysis revealed a higher thermal resistance for esters with longer aliphatic chains in comparison to shorter-chained ones.