A Study On Modified Asphalt With Leaching Residues Of Oceanic Polymetallic Nodules And Cobalt-rich Crusts

This is part work of the Tenth-Five Project (DY105-2-04-14) "The Research ofApply Technology of Oceanic Polymetallic Nodules and Cobalt-rich Crusts LeachingResidues functional filling" managed by China Ocean Mineral Resources R&DAssociation (COMRA). The object studied is the tailings of oceanic polymetallicnodules and cobalt-rich crusts ores after wet extraction(hydrometallurgy)of Ni, Co,Cu, Mn, Zn. After the former systematic study on the chemical composition,substance formation, physical-chemical properties analysis and adsorption capacity ofthe leaching residues, this study focuses on the research of modified asphalt with theresidues, which includes the mixed engineering of the asphalt and residues and ifdifferent proportion effect performance of the asphalt. This paper also discusses themechanism of the residues modified asphalt.Modifying asphalt is an effective way to enhance its intension, temperaturestability, aging resistance and adherence. Currently, there are several modifiedmaterials such as polymer (SBS, SBR, EVA) and inorganic minerals (carbon-black,Nano calcium carbonate, diatomaceous). This paper firstly takes the residues as amodified material to do the research of pavement modified asphalt. By heating (about160℃) and mixing round (the rotate speed is about 600～800 rotate/min), the residuesare added into the asphalt with different proportion (wt %) form 4%, 6%, 8%, 10%to12%. It can be observed that the asphalt has no agglomeration and delamination aftermixed together. This research tests the penetration degree, ductility, softening point,flexibility, viscosity of the asphalt according to the regulations of the experimentalstatute of road engineering asphalt and asphalt mixture, moreover calculates thepenetration index, equivalent softening point T800, equivalent brittle point T1.2. Theresult shows after modified the penetration degree of the asphalt has descended form72 to 55(0.1mm,25℃);penetration index has increased from -1.14to -0.54;softeningpoint and equivalent softening point T800 have increased respectively from88.1℃,47.4℃ t o 101.3℃,49.3℃ , the viscosity has increased from 20.56 to30.88(135℃,Pa·s), the flexibility has increased from 53.5% to 61.9%, the ratio of thepenetration degree after Thin Film Oven Test(TFOT) has increased from 77.7% to87.5%, the ductility at normal temperature stay as much as before, equivalent brittlepoint has descended. It can be indicated that residues modifier can improve the hightemperature stability, temperature susceptibility and aging resistance of the asphalt.This paper analyses the consist and structure changes of the modified asphalt byvarious research measures such as Nuclear Magnetic Resonance Spectroscopy(1H-NMR),Infrared Adsorption Spectrum Analysis(IR)and microscope. Throughthese measures we get a conclusion that in the course of mixing by force, there is noobvious chemical reaction between residues modifier and asphalt. It is mainly thescattering, mixing, absorbing and handing in uniting between the two phases, so ismainly holding altogether in physics meaning, and forms a uniform and steady system.The residues have small gains, they can be dispersed easily, also have large surfacearea. They have a strong absorbing function to suck some compositions among thepitch in holes, thus changed the balance relation between the composition in asphalt.Therefore they increase the viscosity of the asphalt, make asphalt reducing mobilityand enhance the intension.