Effects of Prepared Carbon Nanofibers on Properties of Emulsified Asphalt

To prepare new carbon nanofiber (CNF) for improving properties of emulsified asphalt, CNF-I were first prepared by chemical vapor deposition method. Then the microstructure morphology, specific surface area, pore size distribution, and crystal structure of prepared CNF-I were characterized and compared with those of commercial CNF-II using a field emission scanning electron microscope, automatic specific surface area and aperture distribution instrument, and X-ray diffractometer, respectively. Also, CNF-I and styrene-butadiene-styrene (SBS) latex were utilized to prepare composite modified emulsified asphalt (CS/MEA) and its evaporated residue (ER) samples. Then basic properties of CS/MEA were tested, the dispersity of CNF-I and SBS modifier particles in ER were observed using a confocal laser scanning microscope, and the thermal properties of ER were discussed by using a differential scanning calorimeter. Test results indicate that prepared CNF-I shows cleaner microscopic surface morphology and lower agglomeration degree. The purity and graphitization degree of CNF-I are higher than those of CNF-II, so that the atomic interlaminar force of CNF-I is stronger and the crystal structure is tighter. These improve the surface activity and bonding performance of CNF-I with asphalt. Therefore, CNF-I is selected as a modifier to reinforce emulsified asphalt. Next, basic properties of CS/MEA meet relevant technical requirements. The addition of CNF-I decreases the penetration but increases the softening point of ER. The ductility is first increased and then decreased and reaches the maximum value at the CNF-I content of 0.05 weight percent (wt%). Further, CNF-I forms a spatial network structure in ER and improves the swelling degree of SBS, which causes the phase structure of ER to become more stable. However, when the CNF-I content is higher than 0.05 wt %, the agglomeration occurs to decrease properties of emulsified asphalt. It is found that prepared CNF-I improves properties of emulsified asphalt at the CNF-I content of 0.05 wt %, which is proposed to develop new CS/MEA.