Study on Preparation and Thermophysical Properties of Binary Paraffin Phase Change Concrete

Abstract The binary phase change paraffin (BP) was prepared using the melt blending method, followed by adsorption and encapsulation to produce the phase change aggregate. Phase change concrete was subsequently prepared using the volumetric replacement method. The study examined the thermal properties of BP, along with the semi-adiabatic temperature rise and thermal conductivity of the phase change concrete at different replacement rates. The results indicate that BP exhibits two plateau regions, with phase change intervals varying according to the mass ratio. The high-temperature phase change interval ranges from 18.3 °C to 47.3 °C, while the low-temperature phase change interval ranges from 0.1 °C to 4.6 °C. When the mass ratio of 48# paraffin to 5# paraffin is 7:3, the peak phase change temperatures are 2.58 °C and 44.52 °C, with corresponding enthalpies of 66.52 J/g and 102.63 J/g, respectively. The addition of phase change aggregate effectively reduces the hydration temperature rise of concrete, slows the rate of temperature increase, and decreases the thermal conductivity. The semi-adiabatic temperature rise curve of the phase change concrete exhibits an "S"-shaped variation over time, with the composite exponential function providing a more accurate representation of this process.