Performances Study On Natural Asphalt Modified Asphalt By Plasticizers

At this stage,pure petroleum asphalt is difficult to meet the demand of high-performance asphalt pavement in China.Natural asphalt is favored by road builders due to natural asphalt of the high temperature performance,storage stability,fatigue resistance and aging resistance.However,the natural asphalt has little improvement on the low temperature performance of the matrix asphalt and the high construction temperature is easy to cause problem of aging of the matrix asphalt.In order to solve the above problems,a plurality of modifiers are required to compositely modify the matrix asphalt.The plasticizer in the plastics industry is a high molecular polymer auxiliaries similar in structure to asphalt,plasticizer has the characteristics of anti-aging and low-temperature performance.In view of this,this study used plasticizer to modify the natural asphalt modified asphalt in order to obtain a good composite modification effect and meet the needs of road work.In this paper,softening point,penetration,ductility,Brookfield viscosity,infrared spectroscopy,dynamic shear rheological frequency test and low temperature bending rheology test combined with long-term and short-term aging tests were used to reveal the conventional properties and rheological properties evolution of natural asphalt（Trinidad Lake Asphalt,XRA;Xin Jiang Rock Asphalt,TLA）composite modified asphalt under different plasticizer dosages.In addition,by preparing a composite modified asphalt mixture with different modifier dosages,comparing its high temperature performance,low temperature performance and water stability to determine the optimum amount of each plasticizer modifier.Finally,the modification mechanism was studied by infrared spectroscopy.Through the study of this paper,it is mainly concluded:（1）Conventional properties:DBP,TBC,TOTM plasticizers have significantly improved low temperature crack resistance of ES070#matrix asphalt,K90#matrix asphalt,XRA modified asphalt and TLA modified asphalt.The improvement of low temperature performance is more obvious with the increase of plasticizer content（2%,4%,6%）,but its high temperature performance is reduced.Considering the high temperature performance of asphalt binder,the plasticizer dosage is recommended 4%.（2）High temperature rheological properties:the complex modulus G*of XRA modified asphalt and TLA modified asphalt decreases with the increase of DBP,TBC and TOTM plasticizer,and the phase angleδincreases with the addition of plasticizer keep growing.That is,the plasticizer makes the high temperature fluidity of XRA modified asphalt and TLA modified asphalt increase,and the high temperature stability decreases.When the plasticizer content exceeds 4%,the high temperature grade of XRA modified asphalt and TLA modified asphalt is reduced by one grade,from high temperature PG70to PG64.Moreover,the plasticizer/XRA composite modified asphalt is reduced more than the plasticizer/TLA composite modified asphalt.（3）Low temperature rheological properties:The stiffness modulus S and m values of XRA modified asphalt and TLA modified asphalt decrease with the increase of DBP,TBC and TOTM plasticizer and the phase angleδincreases with the increase of the plasticizer content.That is,the plasticizer increases the low-temperature crack resistance of the XRA modified asphalt and the TLA modified asphalt.The effect of TOTM on the low temperature performance of XRA and TLA modified asphalt is better than DBP.The effect of DBP on the low temperature performance of XRA and TLA modified asphalt is better than that of TBC.（4）Road performance:High-volume DBP,TBC,TOTM plasticizer has a negative effect on the dynamic stability DS of XRA modified asphalt mixture and TLA modified asphalt mixture.It has a positive effect on the tensile strength R_B,the maximum bending strainε_B at the bottom of the beam,the residual stability MS₀,and the residual strength ratio TSR.That is,the plasticizer is detrimental to the high temperature stability of the XRA modified asphalt mixture and the TLA modified asphalt mixture,but it is beneficial to its low temperature crack resistance and water stability.When the amount of plasticizer exceeds 4%,the mixture dynamic stability DS cannot meet the specification.This study suggests that the plasticizer should not exceed 4%of the plasticizer when it is modified by natural plastics.（5）Micro-characteristics:The modification of the natural asphalt is physical modification by the plasticizer of DBP、TBC、TOTM.