Investigation On The Effects Of Warm Mix Asphalt Additives On The Microstructures And Properties Of Polymer Modified Epoxy Asphalts

Epoxy asphalt,as a blend of thermosetting epoxy resin and typically viscoelastic and thermoplastic asphalt,has been widely used in special pavements,especially in steel bridge deck.Crumb rubber(CR)and styrene-butadiene-styrene copolymer(SBS)are commonly used as polymer modifiers for asphalt modification,which make asphalt have excellent low-temperature crack resistance,elastic recovery and high-temperature rutting resistance.In this thesis,waste tire rubber powder and high content of SBS were used to modify the epoxy asphalt binder developed by our laboratory.In addition,Sasobit and waste cooking oil(WCO)were introduced by means of the warm mix asphalt(WMA)technology to achieve the goal of sustainable development and energy saving.The effects of Sasobit on the microstructures and properties of epoxy asphalt rubber(EAR)and epoxy SBS modified asphalt(ESBA)containing high content of SBA were studied.Finally,the effects of WCO on the microstructures and properties of EAR were also studied.Firstly,Sasobit modified asphalt rubber was prepared by mixing industrial asphalt rubber(AR)and warm mix asphalt additive,Sasobit.Then,Sasobit modified AR was used to replace the base asphalt to prepare Sasobit modified EARs.The properties of Sasobit modified EARs were obtained by means of laser scanning confocal microscope(LSCM),dynamic mechanical analysis(DMA),Brookfield viscometer and universal testing machine.The existence of Sasobit reduced the viscosity of the neat EAR and prolonged the construction time of asphalt mixture pavement.The viscosity of Sasobit modified EAR decreased with the increase of Sasobit content.LSCM results showed that spherical and co-continuous two-phase separation microstructures were formed in the neat EAR and Sasobit modified EARs.The presence of Sasobit reduced the number of co-continuous AR particles in the epoxy resin phase.In addition,for Sasobit modified EARs,the number of spherical AR particles increased with the increase of Sasobit content.Quantitative analysis showed that the presence of Sasobit reduced the average particle size and area fraction of AR phase in the neat EAR.DMA results showed that the existence of Sasobit increased the storage modulus(E')of the neat EAR,which indicated that Sasobit improved the stiffness of the neat EAR.The addition of Sasobit slightly reduced the glass transition temperature(T_g)of the neat EAR.In addition,with the increase of the amount of Sasobit,the T_g of Sasobit modified EARs decreased.At the same time,the existence of Sasobit improved the damping properties of the neat EAR.On the other hand,at a lower concentration,the addition of Sasobit improved the mechanical properties of the neat EAR.For Sasobit modified EARs,when the content of Sasobit was 1 wt%,the tensile strength,elongation at break and toughness of the materials were the highest,which were 8%,12%and 15%higher than those of the neat EAR,respectively.Then,Sasobit modified SBA prepared by mixing industrial SBA and Sasobit was used to replace the base asphalt to prepare Sasobit modified ESBAs with high content of SBA.Sasobit reduced the viscosity of the neat ESBA during the whole curing process.For Sasobit modified ESBAs,the viscosity decreased with the increase of Sasobit content.The curly ribbon crystal network structure of Sasobit was observed in Sasobit modified SBA.Sasobit reduced the agglomeration of SBS particles.In the SBA phase of Sasobit modified ESBAs,the crystal network structure disappeared.Sasobit destroyed the spherical microstructure of the neat ESBA.With the increase of Sasobit content,the phase-separated microstructure of Sasobit modified ESBA changed from co-continuous microstructure to phase-inversed microstructure.Sasobit reduced the T_gof the neat ESBA.With the increase of Sasobit content,the T_g of Sasobit modified ESBA decreased.Sasobit weakened the damping properties of the neat ESBA.The damping properties of Sasobit modified ESBA decreased with the increase of Sasobit content.Except for 1.2 wt%,Sasobit decreased the elongation at break and toughness of the neat ESBA.For Sasobit modified ESBAs,the tensile strength decreased with the increase of Sasobit content,but Sasobit increased the Young's modulus of the neat ESBA.Finally,industrial AR was modified by WCO,and then the WCO modified EAR was prepared by mixing with epoxy resin and curing agent.The presence of WCO reduced the number of co-continuous AR particles in the continuous epoxy phase.In addition,for WCO modified EARs,the number of spherical AR particles increased with the increase of WCO content.Quantitative analysis showed that the presence of WCO reduced the average size of AR particles in the neat EAR and improved the dispersion of AR particles.The existence of WCO reduced the viscosity of the neat EAR and prolonged the construction time of asphalt mixture pavement.The viscosity of WCO modified EAR decreased with the increase of WCO content.The construction time of6 wt%WCO modified EAR was extended by 82%.WCO decreased the E'value of the neat EAR,and the flexibility of WCO modified EAR was increased.The existence of WCO reduced the T_g of the neat EAR,which indicated that WCO improved the low-temperature performance of the EAR mixture.In addition,WCO effectively improved the damping properties of the neat EAR.The EAR containing 6 wt%WCO exhibited the best damping properties.The existence of WCO slightly reduced the thermal stability of the neat EAR.The tensile results showed that the addition of WCO increased the elongation at break of the neat EAR,but weakened the tensile strength to a certain extent.