Study On The Adhesion Properties Of Sawdust Bio-oil Modified Asphalt To Aggregate

In order to solve the large consumption of petroleum asphalt in the road and improve the ecological environment,to formulate that the new bio-oil modified asphalt(BMA)material extracted from renewable energy can partially replace petroleum asphalt.BMA is a new type of asphalt material which mixes biomass heavy oil with petroleum asphalt under certain conditions.It has some similar characteristics with asphalt and has certain research value.At present,research in this field mainly focus on the basic properties and road performance characteristics of BMA,and there are few in-depth studies on the adhesion of BMA-Aggregate.The adhesion of asphalt is one of the most important properties of asphalt material.The adhesion is directly related to the performance of asphalt mixture and the damage of asphalt pavement.The analysis of the adhesion of BMA is helpful to promote the practical application of bio-asphalt in the road.Therefore,this paper systematically evaluated the adhesion properties of BMA-Aggregate from a macro and micro perspective.The main research contents and results include the following aspects:First of all,the preparation process of BMA was determined through the existing research and biomass sources to produce BMA.The correlation between the basic performance of BMA and the content of bio-oil was analyzed.According to the test results of three major indexes,the range of BMA was determined to be 5%-40%.Secondly,the adhesion of BMA-aggregate with different bio oil content was evaluated qualitatively and quantitatively.According to the test results of traditional boiling method in current code,the adhesion of BMA-aggregate was qualitatively evaluated.Ultrasonic simulated hydrodynamic pressure method and Image-Pro Plus(IPP)software were used to calculate the spalling rate,average spalling rate and spalling rate of BMA on the aggregate surface at time points,respectively,to complete the qualitative and quantitative evaluation of BMA,with the increase of bio-oil content,the spalling rate increases,and the adhesion of BMA-aggregate becomes worse gradually.Then,Atomic Force Microscopy(AFM)was used to observe and analyze the surface microstructure and Force curve of BMA with different dosage,and the adhesion of BMA to aggregate was evaluated at the micro scale."Bee-structure" of the BMA surface was obtained by AFM off-line Analysis software Nano Scope Analysis,and the test pictures were processed and imported into IPP software to calculate the size and area ratio of the "bee-structure" as well as the roughness value of the asphalt surface to analyze the surface roughness of the BMA.The surface adhesion forces of different BMA were obtained through force curve analysis,and the conversion from adhesion force to adhesion work and surface energy was completed based on JKR theory.The qualitative and quantitative evaluation of micro-adhesion of BMA was completed based on surface energy.With the increase of bio-oil content,asphalt surface adhesion force decreases,surface energy decreases,and asphalt adhesion ability becomes worse.Finally,combining with the macro to micro adhesion test results,through the SPSS software to draw BMA finally peeling rate,bee total area ratio,asphalt integral to the correlation between surface energy curve,and based on the level of significance analysis,finally concluded,macro to micro adhesion rate of the end of the test results of spalling and BMA surface can have strong correlation.