| China is one of the largest countries in rubber consumption,and a large number of waste rubber remains unused to cause environmental pollution.The addition of waste rubber into rubber powder can improve the high temperature stability,low temperature crack resistance,water stability and durability of modified asphalt.The use of waste rubber powder in the modified asphalt can deal with a large number of waste rubber,reduce environmental pollution and reduce the use of matrix bitumen.The cost of road construction can be saved by the low cost of rubber powder compared with other modifiers.However,the compatibility between rubber powder and matrix asphalt is poor,storage stability is not good,rubber po’wder is easy to segregate,which restricts the popularization and use of rubber asphalt.Based on this,the modification mechanism and storage stability of rubber asphalt are studied in this paper.The preparation technology of industrial production was simulated,and the influence of the number of rubber powder and the amount of rubber powder on the performance of rubber asphalt were analyzed.The infrared spectrum shows that there are both physical and chemical reactions between rubber powder and matrix asphalt.The SEM test showed that the rubber bitumen changed from granular to reticular formation with the increase of development time,and the rubber bitumen formed a relatively stable two phase continuous structure.The relationship between the change law of asphalt four components and the performance of asphalt is analyzed.The asphaltene has been increasing,the saturation point is reduced first,the aromatic fraction has been reduced,the gum has been increased,the asphaltene is increased and the needle penetration is reduced,the viscosity and softening point of the lightweight components are increased and the ductility is reduced.The experiment of extracting the insoluble content of toluene found that the process of desulphurization and degradation of rubber powder began in the early stage of the preparation of rubber bitumen,and the quality loss of the rubber powder decreased with the time.When the reaction time is 30min,the mass loss at 180℃ is 8.2%,and the mass loss at 200℃ is 17.5%.It shows that there is not only swelling reaction but also a large amount of chemical reaction in the early preparation of rubber bitumen.The change rule of the softening point difference of rubber bitumen with different rubber powder content,different contents,different storage temperature,different time and mechanical agitation is studied.The increase of rubber pitch and the increase of the content of rubber powder make the viscosity of rubber bitumen become larger.The larger viscosity hinders the movement of rubber particles and is not easy to segregate,so the storage stability is stable.Sexual improvement.Low storage temperature,storage time not exceeding 12 hours and mechanical stirring before use are favorable for homogeneous phase of rubber asphalt.Different proportions of common rubber powder and desulphurized rubber powder were added to study the change of conventional properties.When the total amount of the rubber powder is constant,the viscosity of the rubber bitumen is reduced,the low temperature ductility and the compatibility are improved and the storage stability is improved.But the amount of desulphurization rubber powder is too large,the degrading of the desulfurized rubber powder is more,the small molecules of the asphalt are too much,and the gel membrane between the ordinary rubber powder can not contact the crosslinking structure effectively.Although there are more chemical reactions,it is still easy to cause the segregation of rubber particles,which makes the storage stability decrease.For bitumen 70,17.5%common rubber powder+7.5%desulfurized rubber powder modified asphalt has better comprehensive properties.Fluorescence microscopy showed that the compatibility of modified asphalt with ordinary rubber powder and desulphurized rubber powder was improved.According to the macro and micro research,the structural model of modified asphalt with common rubber powder and desulfurized rubber powder is put forward.The effects of SBS,aromatic oil,TOR,silane coupling agent and stabilizer A were added to the 17.5%ordinary rubber powder+7.5%modified bitumen,and the effects of different admixtures on the properties of modified asphalt were studied.The formulation of high performance rubber asphalt based on high storage stability was developed,that is the A formula of 17.5%ordinary rubber powder+7.5%desulphurization rubber powder+2%SBS+4%arene oil+4.5%TOR(accounting for the quality of rubber powder)+3%stabilizer.Compared with the ordinary rubber powder of 25%,the brucell viscosity at 175℃ was 2.84Pa S,decreased by 31%,the softening point was 81℃,increased by 18%,25℃ centigrade is 54.6,5℃ ductility is 272mm,increased by 213%,and softening point difference is 0.7℃,decreased by 91%.DSR test shows that the high performance rubber asphalt developed in this study has good viscoelastic stability and high temperature rutting resistance.The compatibility of rubber asphalt with different formulations was observed by fluorescence microscope,indicating that the high performance rubber asphalt developed in this study has good compatibility.The high performance rubber bitumen developed in this study has no change in the high temperature performance and water temperature performance of the PAC-13 mixture prepared by the storage of 48h at 165℃.Through the experimental study,it is believed that to improve the high temperature performance,low temperature performance and storage stability of rubber bitumen,it is necessary for the rubber powder to have sufficient swelling to form crosslinking structure;the chemical bond is formed between the rubber powder,the matrix asphalt and the admixture,and the crosslinking structure in the modified bitumen is more stable and compatible through the action of the chemical bond.It is better that the continuity of molecular weight between substances ensures that it forms a homogeneous and stable phase state. |
PDF Full Text Request