Research On Carbon Emission Assessment Technology For Asphalt Pavement Construction And Maintenance Process

The accumulation of greenhouse effects is an important cause of global warming,and the annual huge fossil energy consumption in the world will generate a considerable amount of greenhouse gas emissions.To this end,countries have established carbon emissions trading systems to achieve emission reduction goals.In 2017,China started the construction of a carbon emissions trading system.The road industry has a considerable amount of carbon emissions and has a good prospect of carbon emissions trading.Establishing a carbon emission calculation model for asphalt pavement is of great significance for China's highway industry to participate in carbon emissions trading.Based on the life cycle analysis method,this paper establishes the theoretical basis of the carbon emssion calculation model,sets the model boundary and divides the calculation model into the raw material production and transportation stage model,the construction stage model and the maintenance and maintenance stage model according to the asphalt pavement life cycle stage.The road industry standard is used as the design basis of the model calculation method and the basis of the main model parameters,and some parameters are used to study the literature data.develope carbon emission calculation software for asphalt pavement was based on the carbon emission evaluation model with Excel+VB A.Finally,study the carbon emission of the asphalt pavement structure type,the emission reduction effect of the warm mix asphalt mixture and the impact of different conservation measures on carbon emissions.Using asphalt pavement carbon emission evaluation model to evaluate the carbon emissions of different asphalt pavement structure types,the carbon emissions of the three asphalt pavement structure types are basically same at all stages,material production process are the largest proportion,followed by the construction phase,the total amount of carbon emissions produced by the material transport process smaller.Among them,the material production process and the construction phase are the main stages of carbon emission,and the proportion of them has reached more than 90%of the building period.In the material production process,the total carbon emissions of the materials production of the two composite base asphalt pavement structures are less than the semi-rigid base asphalt pavement structure,which are 74.1%and 75.2%of latter respectively.The main reason for the difference is that the amount of cement used in the semi-rigid layer asphalt pavement is large,causing more carbon emissions.In the construction phase,the difference in carbon emissions of the three asphalt pavement structure types is mainly reflected in the mixing process of the mixture.Because the average carbon emissions per unit volume of pavement solid asphalt mixture is 4.9 times that of water-stabilized mixture,the thickness of asphalt layer is the main influencing factor of carbon emissions during construction phase.The analysis results of the effect of warm mix asphalt mixture emission reduction show that the foamed warm mix asphalt can make the carbon emission reduce 3.87kgCO2e of in the mixture mixing process,and the emission reduction rate is 18.7%.When adopted warm mixing technology with warm-mixed agent,the carbon emission caused by the production of warm-mixed agent should be considered,and the emission reduction amount is reduced to 1.66kgCO2e,and the emission reduction rate is 8.0%.By comparing the effects of different warm mix asphalt mixtures,it is known that the average annual carbon emissions generated by each maintaining measures from small to big are ultra-thin wear surface,micro-surfacing,in-place hot recycling and milling&resurfacing.The micro-surfacing and the ultra-thin wear surface are only 51%and 46%of the milling&resurfacing.