Promoting the dispersion of LDHs powder in bitumen with pre-dispersion and microwave heating

Layered Double Hydroxides (LDHs) are a family of intercalated functional materials with a layered structure and regarded as an effective modifier to improve the UV ageing resistance of bitumen. However, the preparation of LDHs modified bitumen is very complicated and time-consuming. Based on the theory of Stokes' law and the equation of the terminal velocity, pre-dispersion and microwave heating were proposed in this research to promote the dispersion of LDHs powder in bitumen matrix. LDHs modified pre-dispersed bitumen (LDHs-PDB) particles were first prepared and then were dispersed in bitumen matrix with the assistance of microwave heating. The cosolvent was optimized and the dispersion of LDHs in the modified bitumen was characterized by the laser particle size analyzer. It is found that the utilization of pre-dispersion alone could slightly improve the dispersion of LDHs in bitumen. The combination of pre-dispersion and microwave heating significantly improved the dispersion of LDHs in bitumen matrix. Although the distribution is still not uniform, it is believed that a reasonable design of the size distribution of LDHs-PDB particles may result in a uniform vertical distribution of particles in bitumen matrix. (C) 2015 Elsevier Ltd. All rights reserved.