Synthesis and Property of a Green Melting-Snow Additive for Asphalt Pavement
Mg-Al Cl-layered double hydroxide (LDH) was prepared from Mg-Al CO32-LDH by the calcination recovery method. Energy dispersive spectroscopy (EDS) spectra proved that Cl-anions replaced CO32-anions in the LDH structure. Scanning electron microscopy (SEM) images showed that the platelet thickness of Mg-Al Cl-LDH were larger than those of Mg-Al CO32-LDH. This increase in the structural dimensions occurred because of that a larger quantity of monovalent Cl-anions had substituted divalent CO32-anions. The result of freezing temperature tests indicated that Mg-Al Cl-LDH is more effective than Mg-Al CO32-LDH in melting snow. Conductivities of immersion liquids testified that Cl-anions are restricted in asphalt mixtures by Mg-Al Cl-LDH without negatively affecting the surrounding environment and pavement. Snow melting rates for Mg-Al Cl-LDH before and after immersion did not change, indicating that rain did not weaken the effect of Mg-Al Cl-LDH on melting snow and thus did not pollute the environment.