Xinyu Li,Denghui Ren,Shencheng Fan,Zibo Lin,Fanyu Meng,Haisheng Wu,Fang Lai,Jing Li
The utilization of spent cathode carbon blocks (SCCB) from aluminum electrolysis has become challenging due to their content of highly toxic cyanides and environmentally harmful fluorides. To achieve reliable recovery and utilization of hazardous waste , targeted research has been conducted on the treatment of waste cathode carbon blocks and their potential application in asphalt pavement . Hydrogen peroxide (H 2 O 2 ) is employed to remove cyanides from the waste cathode carbon blocks, meeting the construction requirements for transportation areas. Anhydrous calcium chloride is used as a calcium source to precipitate soluble fluorides in the solution. Finally, the waste cathode carbon blocks are gel-crosslinked using polyvinyl alcohol-polyvinyl pyrrolidone, addressing the release of fluorides beyond environmental tolerance. This results in the synthesis of a composite material consisting of calcium fluoride deposits and gel-encapsulated waste cathode carbon blocks (PSB), which exhibits good thermal stability in the temperature range of 0–217 °C. Through DSR and MSCR testing, it has been demonstrated that the gel-crosslinked waste cathode carbon block composite material improves the asphalt's sensitivity to temperature and enhances its resistance to rutting at high temperatures. The 1% PSB/SBS modified asphalt shows the best performance, compared to SBS, the complex modulus (G*) of the modified asphalt increased by 117.4% at 46 °C, and the recovery indices for creep at 64 °C improved by 39.28% (at 0.1 kPa) and 55.65% (at 3.2 kPa), and thermal gravimetric analysis of the asphalt confirms that the addition of PSB improves the asphalt's thermal stability. Fluorescence microscopy analysis reveals that the inclusion of PSB does not affect the morphological development of SBS swelling and plays a stabilizing and supporting role in the asphalt mixture .
Tao Liu,Naisheng Guo,Xin Jin,Yiqiu Tan,Zhanping You,Shichao Cui,Zhaoyang Chu,Chenze Fang
Phase change materials (PCMs) can regulate asphalt temperature through thermal storage properties to prevent thermal damage in asphalt pavements. However, the effects of PCMs on the thermoregulation and rheological properties of asphalt require further study. In this study, polyurethane solid–solid phase change materials (PUSSPCMs) were prepared to impart thermoregulation properties to asphalt, and the effects of PUSSPCMs on the rheological properties and microscopic characterization of asphalt were investigated. The PUSSPCMs were produced by different soft segment mass fractions (70 %, 80 %, and 90 %), and they were used to prepare modified asphalt with varying contents (3 %, 5 %, and 7 %). Thermoregulation testing system, dynamic shear rheology (DSR), bending beam rheology (BBR) tests, differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were conducted to determine the thermoregulation, rheological properties, and modification mechanism of PUSSPCM-modified asphalt, respectively. The results show that the thermoregulation property of PUSSPCM-modified asphalt improves with the increase of soft segment mass fraction and content, 7 % P90 asphalt exhibits the best thermoregulation property with the excellent delayed time (1105 s) and temperature difference (7.1 ℃). The high-temperature rutting resistance of the modified asphalt is enhanced by decreasing the soft segment mass fraction and increasing the content of PUSSPCMs, with the 7 % P70 being the best asphalt type. The 7 % P90 asphalt exhibits the optimum low-temperature creep performance due to a higher soft segment mass fraction. The modified asphalt may be a physical modification since no new characteristic peaks appear. With the increase of soft segment mass fraction, the PUSSPCMs in asphalt transform from elastomer to a ribbon-like structure. Furthermore, the microscopic roughness ( S q ) and Young's modulus of the modified asphalt decline with the increase in soft segment mass fraction and content of PUSSPCMs, implying an increase in microscopic crack resistance and a decrease in elasticity.
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