Research On The Performance Of Rice Husk Ash/Crumb Rubber Powder Modified Asphalt Binder And Mixture

In recent years,with the development of economy and infrastructure construction,the amount of agricultural and industrial waste is increased.Improper treatment and use will lead to environmental pollution.At the same time,the performance and economic cost of building materials are the main concerns of experts and specialists.Therefore,the development and utilization of waste materials to be used as a new type of building materials has become the consensus of researchers,and it is also the trend of social development.Rice husk and rubber are two kinds of waste materials.Improper disposal of them will not only cause environmental pollution,but also a waste of resources.Hot mix asphalt mixture(HMA)is the main pavement material of asphalt pavement.Due to the viscoelastic properties and temperature sensitivity of asphalt,under the influence of load and temperature,asphalt pavement is prone to rutting,fatigue cracking,temperature shrinkage cracking and other distresses which reduces the service condition and service life of the pavement.Especially in high-temperature areas(Sudan as a typical representative),rutting has become the main distress of asphalt pavement.Therefore,improving the asphalt mixture of high and low-temperature performance has an important role in improving road asphalt pavement performance.The high and low-temperature performance of base asphalt mixture can be improved by adding modifiers.The addition of rice husk ash(RHA)and crumb rubber powder(CRP)into asphalt to improve the performance of asphalt and asphalt mixture will not only enhance the high and low-temperature performance of asphalt pavement,but also the use of RHA and CRP to form a new modifier could consider as one of the proper management of the waste which ensures economic and environmental benefits.Therefore,this research has a good economic and environmental benefits.This research was mainly focused on the effects of RHA/CRP composite modifier on the high-temperature performance of base asphalt and its mixture.Different dosages of composite modifiers of RHA(1%,4%,and 7%)and CRP(5%,10%,and 15%)by weight of asphalt binder were designed and mixed with base asphalt to prepare modified asphalt.Several laboratory experiments(penetration test,softening point,elastic recovery test,rotational viscometer test,dynamic shear rheometer test,and multiple stress creep recovery test)were conducted to determine the physical and rheological properties of the different RHA/CRP composite modified asphalt samples.The effect of RHA/CRP composite modifier on asphalt performance was analyzed,and reasonable amount of RHA/CRP composite modifier was determined.In order to study the anti-aging properties of RHA/CRP composite modified asphalt,the rolling thin film oven(RTFO)test was conducted to simulate aging on a short term in the laboratory.Moreover,Fourier transform infrared spectroscopy(FTIR)test and scanning electron microscope(SEM)were used to study the modification and aging mechanisms,besides analyzing the microstructure of the modifiers and modified asphalt.In addition,the Marshall stability test,indirect tensile strength test and rutting test of RHA/CRP composite modified asphalt mixture were carried out to compare and analyze the high-temperature stability of RHA/CRP composite modified asphalt mixture.The obtained results indicated that:Adding RHA/CRP affected positively the high-temperature performance of asphalt binders by increasing softening point,elastic recovery,viscosity,complex modulus,rutting factor,failure temperature,percent recovery,and penetration index,reducing penetration,phase angle as well as non-recoverable creep compliance(Jnr).The addition of RHA/CRP had significant positive effect on the aging resistance of asphalt binder through increasing penetration aging ratio(PAR)values.Nevertheless,adding RHA and CRP reduced softening point increment(SPI),viscosity aging index(VAI),as well as the rutting factor aging index(AIOR).Investigating the aging mechanisms of RHA/CRP modified asphalt before and after aging through the changes in functional groups of the modified asphalt binders indicated that during the short-term aging process,the functional groups in spectrum are basically the same with change in the peak intensity.Moreover,SEM images showed that RHA/CRP was uniformly dispersed within asphalt binder.Taking comprehensive consideration of performance tests,results showed that the higher the content of RHA/CRP was,the better the high-temperature performance was.However,modified with high concentration of RHA/CRP failed to meet the requirement of viscosity.Therefore,the optimal content of composite modified asphalt was(7%RHA+10%CRP).The Marshall stability and indirect tensile strength of asphalt mixture were greatly improved after adding RHA/CRP composite modifier.Compared with base asphalt mixture,the asphalt mixture modified by RHA/CRP composite modifier had better high-temperature stability and was less susceptible to rutting.The intermediate and low-temperature performance of the optimum RHA/CRP content(7%RHA+10%CRP)were evaluated through conducting four bending beam test,bending beam rheometer(BBR)test,and low temperature bending test.Compared with unmodified asphalt and its mixture,(7%RHA+10%CRP)modified asphalt binder and its mixture had a better intermediate and low-temperature performance.In addition,compared with SBS modified asphalt mixture,the(7%RHA+10%CRP)modified asphalt mixture showed better anti-rutting performance.In summary,the(RHA/CRP)modified asphalt with a percentage of(7%RHA+10%CRP)and its mixture had higher rutting resistance,which can be used for asphalt pavement in the high-temperature area.Therefore,the research results can provide a new pavement material with better performance and low cost for the construction of asphalt pavement in high temperature area(Sudan).