Preparation And Characterization Of Polymer Modified Epoxy Asphalts

As one of thermosetting resin modified asphalt,epoxy asphalts(EA)have been widely used on the pavement of orthotropic steel bridge decks,due to its excellent intensity and good resistance to aging and chemical attack.However,during the long-term usage,fatigue cracks and other diseases of epoxy asphalt mixture often occur,which are related to the lack of low-temperature toughness of epoxy asphalts.In order to improve the low-temperature toughness of epoxy asphalts,polymer modified domestic hot-mix epoxy asphalts binders(HEAB)were prepared in present thesis.The influence of thermoplastic elastomer and plastomer on the performance of epoxy asphalt was studied.First,styrene-butadiene-styrene(SBS)modified asphalts(SA)were prepared by using thermoplastic elastomer SBS,and the SBS modified epoxy asphalts(ESA)were prepared by mixing the SA with epoxy resin and curing agent.There are two sources of SA:industrial and self-prepared.The viscosity,thermal stability,mechanical properties,and morphology of SBS modified epoxy asphalts were investigated by Brookfield rotational viscosmeter,thermogravimetric analysis(TGA),universal test machine,scanning electron microscopy(SEM)and laser scanning confocal microscopy(LSCM),respectively.The influence of SA content and SBS content on the properties of SBS modified epoxy asphalts were investigated,respectively.The addition of SBS increases the viscosity of EA.The viscosities of ESA increase with the contents of SA and SBS.It is worth mentioning that the viscosity of all the SBS modified epoxy asphalts can reach the technical requirements of viscosity for HEAB.The addition of SBS improves the thermal stability of EA.With the increase of SA and SBS contents,thermal stability of ESA also increases.SBS has a significant toughening effect on the epoxy asphalts.In addition,the industrial SA is more effective in improving the toughness of epoxy asphalts.LSCM observation shows that phase-separated structure exists in SBS modified epoxy asphalt.For ESA prepared with industrial SA,epoxy resin is continuous phase and SBS modified bitumen is dispersed phase.Phase inversion does not occur in SBS modified epoxy asphalt when the content of SA reaches 60 wt%.The existence of SBS leads to the dispersion of asphalt in the continuous epoxy to be more uniform.For ESA prepared with self-prepared SA,the size and dispersion of the dispersed phase in the ESA vary slightly when the content of SBS is less than 4 wt%.However,when the content of SBS reaches 4 wt%,the particle size and distribution of SA in the epoxy become significantly larger and wider.SBS modified epoxy asphalt can fully meet the construction requirements of viscosity,mechanical properties and thermal properties for hot mix epoxy asphalt mixture.In particular,the industrial SBS modified asphalt can significantly improve the toughness of epoxy asphalt,which is helpful to solve the problem of low-temperature fatigue cracks of epoxy asphalt.Second,novel polyolefins,Honeywell Titan(HON)polymers(HON7205 and HON7686),modified HEAB were investigated.On the basis investigation of structure and thermal properties of HON polymers,the effects of HON polymers on the viscosity,thermal stability and mechanical properties of HEAB were characterized.Results indicate that HON7205 and HON7686 are polyethylene and polyethylene wax with low molecular weight,respectively.HON 7686 has much higher melting point,crystal temperature and crystallinity than the HON7205.The presence of HON polymers increases the viscosity and thermal stability of HEAB.Besides,HON7686 can improve the viscosity and thermal stability of HEAB more significantly.The addition of HON polymers slightly increases the elongation at break of EA.However.tensile strength,toughness and Yooung's modulus of FA decrease with the incorporation of HON polymers.In a word,thermoplastic elastomer,especially industrial SBS modified asphalt can significantly improve the toughness of epoxy asphalt.Despite the novel plastomer HON polymers can slightly improve the elongation at break of epoxy asphalt,the toughness of epoxy asphalts slightly reduce.As a result.SBS is more suitable for use as a modifier to improve the toughness of epoxy asphalt.