Effectiveness of the different eutectic phase-change materials in cooling asphalt pavement

Abstract

Choosing a phase-change material (PCM) adapted to the specific phase-change temperature (Tm) required for each temperature condition is of utmost importance in cooling pavements. Eutectic phase-change materials (EPCMs) realize the customization of the desired Tm and reduce the difficulty of matching PCMs. This work aims to investigate the effectiveness of a group of binary/ternary EPCMs with Tm ranging from 30 to 60 ℃ and melting enthalpies of around 200 J/g as thermal regulation components for different asphalt. To achieve this goal, the thermal and rheological properties of phase-change asphalt binders (PCAB) were evaluated by differential scanning calorimeter, thermogravimetric, Fourier transform infrared, and multiple stress creep and recovery tests. The results showed that PCAB with latent heat improved the specific heat capacity, which brought a maximum temperature lag of 134.5 min and a maximum temperature difference of 11 ℃. Similarly, the PCAB remained chemical stability, and its thermal stability complied with the construction temperature specifications. However, the recrystallization of EPCMs was impeded by the molten asphalt binder matrix, resulting in a significant reduction in both the Tm and enthalpy. Therefore, these reductions should be taken into consideration when choosing an EPCM. Additionally, as liquid EPCM softens the binder, the absence of elasticity in solid EPCMs renders the binder stiff, thus reducing its resistance to deformation. These impacts were particularly noticeable in Styrene-Butadiene-Styrene modified asphalt due to the polymer network being dissolved by liquefication-EPCMs. To sum up, EPCMs with a higher Tm (40–60 ℃) may decrease their negative impact on deformation resistance, such as palmitic acid-myristic acid-methyl stearate mixtures.