| The waste rubber powder modified asphalt is applied in the field of road engineering because of its outstanding performance and taking into account the concept of green,coordinated and sustainable development,but its poor compatibility,large viscosity and other shortcomings limit its promotion and application in a wider range.In order to solve the technical shortcomings of traditional waste rubber powder modified asphalt,Terminal Blend technology has been developed gradually.The technology uses asphalt as the solvent for the treatment of rubber powder particles,desulfurization and cracking of rubber powder particles at a higher temperature and a longer time.In the effective solution of rubber asphalt poor compatibility,viscosity and other shortcomings,but also brought the asphalt aging,high temperature performance is poor and other new problems.Therefore,this paper continues the idea of Terminal Blend technology,uses naphthenic oil with stable properties instead of asphalt as the pretreatment solvent of rubber particles,and carries out a series of research on the properties and mechanism of the new pretreatment rubber powder modified asphalt.Firstly,the pretreatment process was studied,and the "one-to-one" relationship between the solubility and the macro properties was directly established by replacing the pretreatment temperature and time with the solubility.And the optimal solubility(the optimal pretreatment process)under the premise of ensuring the compatibility of rubber asphalt was determined by three indexes and viscosity experiment,storage stability experiment and high and low temperature rheological experiment.Secondly,the relevant mechanism of improving the compatibility of rubber asphalt with the pretreatment method in this paper was studied.The main difference was the solubility that could be achieved by adding asphalt,the rubber particles with different treatment processes were distinguished,and the changes of their main functional groups were studied and analyzed by infrared spectroscopy(FTIR)experiment.The molecular weight was characterized by gel permeation chromatography(GPC),and the surface morphology was studied by scanning electron microscopy(SEM).The modification mechanism was revealed.Finally,the content of pretreated rubber powder was studied,and the optimal content was determined by three indexes,viscosity experiment and high and low temperature rheological experiment.In the later study,low density polyethylene(LDPE)was mixed with different contents to make up for the loss of its high temperature performance,and the content of low density polyethylene(LDPE)was studied.The main research results are as follows:(1)Using naphthenic oil as pretreatment solvent can effectively desulfurize and crack rubber powder particles.The compatibility of rubber asphalt can be improved effectively by destroying the internal network structure of the particles and forming irregular structures such as folds,holes and grooves on the surface.(2)When the solubility reaches more than 75%,rubber asphalt with good compatibility can be obtained to meet the needs of medium and long distance transportation in engineering.Its low temperature cracking resistance is significantly better than that of traditional wet waste rubber powder modified asphalt,but its high temperature stability is insufficient.(3)The pre-treated rubber powder modified asphalt with 20% content has excellent compatibility and balanced high and low temperature performance.On this basis,the combination of 1.5% low density polyethylene(LDPE)can significantly improve the high temperature stability of rubber asphalt.Although the low temperature cracking resistance is slightly reduced,it still has significant advantages compared with the traditional wet waste rubber powder modified asphalt.The composite modified asphalt with 20% pretreated rubber powder and 1.5% low density polyethylene has good compatibility,high and low temperature performance,and has the potential to be used in a wide range of engineering. |
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