Research On Road Performance And Mechanism Of Bio-asphalt Modified By Rock Asphalt And Montmorillonite

China’s transportation infrastructure has been booming since the implementation of strong transportation network strategy plan.During this period,a lot of resources have been consumed in the past highway construction work.It is estimated that about 40 million tons of asphalt were consumed in China every year for road construction and maintenance.The contradiction between limited crude oil inventory and the growing demand petroleum asphalt in road engineering has become increasingly prominent.The asphalt industry in China will face a situation of short supply for a long time.It is urgent to develop alternative asphalt materials and reduce the amount of non-renewable asphalt resources.Bio-asphalt is a green,widely sourced and renewable new asphalt material.The method of using bio-oil to replace part of petroleum asphalt has showed good economic and environmental protection.However,the anti-aging and high-temperature rutting resistance of bio-asphalt are insufficient,which limits the application of bio-asphalt in roads.Based on this,this research selects rock asphalt and montmorillonite to modify bio-asphalt,in order to improve its high temperature performance and anti-aging performance,and increase the proportion of bio-oil instead of petroleum asphalt.The optimum dosage of each modifier was determined by the three indexes of modified asphalt and rotational viscosity.At the same time,the rheological properties and anti-aging properties of rock asphalt-montmorillonite composite modified bio-asphalt were explored under the optimum dosage.The Fourier infrared spectroscopy test and scanning electron microscopy test were used to explore the mechanism of composite modification,so as to guide the modification process of rock asphalt-montmorillonite composite modified bio-asphalt.The research results show that,bio-oil contains much of light components.Fortunately,parts of them are absorbed by distilled water with the help of constant temperature water bath treatment.According to the orthogonal test,the optimal ratio of rock asphaltmontmorillonite composite modified bio-asphalt with 7%bio-oil,30%rock asphalt and 5%montmorillonite was determined.The ductility and softening point of bio-asphalt were improved,and the penetration was reduced.Additionally,the water bath treatment,the addition of rock asphalt and montmorillonite can improve the high-temperature rheological properties of bio-asphalt to varying degrees.Its rutting factor at 64℃ is 2.6 times that of the bio-asphalt.The high temperature performance of the composite bio-asphalt has obvious advantages over the bio-asphalt treated with single measure.In terms of the low-temperature rheological properties of composite bio-asphalt,the three treatment measures mentioned above deteriorated the low-temperature performance of bio-asphalt.However,the low-temperature performance of composite modified bio-asphalt can meet the requirements of SHRP for low temperature performance of asphalt binder.Otherwise,the stiffness modulus of composite modified bio-asphalt is 0.87 times that of matrix asphalt,and the creep rate is 1.03 times that of matrix asphalt.At the same time,the composite modified bio-asphalt has smaller complex modulus aging index(CMAI),stiffness modulus aging index(SAI),carbonyl index(Ic=o)and sulfoxide index(Is=o)),along with a larger phase angle aging index(PAAI)and creep rate aging index(mAI),This indicated that the anti-aging performance of bio-asphalt was enhanced.Finnally,infrared spectroscopy experiments show that the mixing of rock asphalt,montmorillonite,bio-oil,and matrix asphalt is a physical blending process.Scanning electron microscope test results show that bio-oil improves the uniformity of the dispersion of rock asphalt and montmorillonite in the asphalt.