Environmental Impacts Of Chinese And Norwegian High-grade Asphalt Roads Based On LCA

The quantitative analysis of asphalt road environmental load by Life Cycle Assessment（LCA）method has become an academic hotspot widely discussed in the road transportation industry in recent years,and it is also the key research content of implementing energy-saving and emission reduction road construction technology.However,current research only focuses on the investigation and analysis toward domestic asphalt pavement,ignoring the overall structure of asphalt road and effective comparison with international countries.Norway has introduced the life cycle environmental value into the construction of large-scale highway projects in2017.The structural design,technical path and service conditions of its asphalt roads are quite different from those of most regions in China.Therefore,this study comprehensively quantified and compared the life cycle environmental loads of Chinese and Norwegian asphalt road,establishing a complete practical construction data and quantitative evaluation system based on quantitative methods and results,and proposing the development strategy for green road construction technology in China.The main research contents and conclusions of this study can be summarized as follows:（1）Proposed the characterization method for road environmental impacts based on the typical asphalt pavement structures in China and Norway,and using the primary data in pavement construction processes to carry out quantitative characterization of energy consumption and greenhouse gas emissions of asphalt pavement overall structure.The results found that energy consumption and pollution emission of surface layer are the main sources of road environmental loads.The energy consumption of Chinese surface layer accounts for 44.07%and GHG emission 42.37%compared with the overall road structure,while the energy consumption of Norwegian surface layer accounts for 28.00%and GHG emission is 27.56%.In the Chinese typical asphalt road structure,the energy consumed in the life cycle of surface layer is 5.14TJ,accompanied by 385.22t equivalent CO₂,while 83J energy consumption and352.59t equivalent CO₂production are caused by Norwegian wearing layer and binder layer.The analysis of gas detection on the asphalt pavement construction site shows that among paving site,laboratory,mixing plant and asphalt storage tank,the VOC concentration of asphalt storage tank is the largest,and the release amount is close to110ug/L,which is 2-27 times of asphalt mixing plant and paving site.The VOC concentration of asphalt laboratory can reach to 15.60ug/l,approximating 4 times of VOC concentration（4.08 ug/L）in the construction site.Therefore,the VOCs emission during the whole process of asphalt material use and service should be fully considered as analyzing the environmental impacts of asphalt surface life cycle.During the whole life span,the energy consumption and emission of Norwegian road are higher than those in China due to the structural design of antifreeze layer and snow climate condition.Chinese asphalt road consumes energy about 11.38 TJ and emit 873.22 t of equivalent CO₂in functional units.However,the whole structure life cycle of Norwegian asphalt road results in 13.68 TJ energy consumption and 1281 t GHG emission.Moreover,considering the differences of material types and transportation,the energy consumption of asphalt pavement construction in Norway is 0.79-1.13 TJ,and the GHG emission is 51.94-74.88 t,resulting in significantly lower environmental load than Chinese high-grade asphalt pavement.（2）Targeting three kinds of low-environmental load asphalt pavement construction technologies,namely warm mix asphalt pavement,induction self-healing asphalt pavement and steel slag recycling asphalt pavement,the quantitative analysis of environmental impact is carried out.The research shows that the environmental loads low-environmental load asphalt pavement construction is closely related to the recycling of materials,the distance of material transportation and the climatic characteristics.The energy consumption and GHG emission of hot mix asphalt mixture are 4.16 TJ and 337.47 t,respectively,while that of steel slag asphalt pavement is 4.39TJ.The energy consumption of self-healing and warm mix asphalt pavement is 4.24 TJ and 3.59 TJ,respectively.The GHG emission of self-healing asphalt pavement is 313.64 t,and that of steel slag recycling and warm mix asphalt pavement is 297.31 t and 238.74 t,respectively.Compared with the surface layer construction of three low-environmental load asphalt pavements,it is found that the asphalt mixture of steel slag is relatively large,and the self-healing asphalt mixture results in the greater environmental loads than that of the hot mix asphalt mixture because of the addition of steel fiber.The warm mixing asphalt can reduce the energy consumption and emission by effectively reducing the mixing and construction temperature of asphalt mixture.（3）Considering the material production,material transportation,mixture mixing,asphalt mixture transportation and pavement construction,a fast and accurate quantitative calculation system of asphalt pavement environmental loads is established,which realizes the quantitative characterization of environmental load of asphalt pavement in its whole life cycle,and then summarizing the development direction of energy saving and emission reduction asphalt pavement.By analyzing the distribution structure of asphalt pavement construction process,the environmental impacts assessment framework of asphalt pavement construction is established.Meanwhile,based on the quantitative results of energy consumption and emission of Chinese and Norway asphalt road,the paper establishes the asphalt road environmental load quantitative system APEAT combined with the principle of LCA.the system framework,data acquisition mode and calculation model of APEAT are interpreted.The results show that the policy improvement of energy saving and emission reduction road in China should focus on the planning and management of raw materials,the application of advanced road construction and maintenance technology,the utilization of new energy in road projects,and the awareness of road ecological construction.The results of study make up for the blank of Chinese high-grade asphalt roads whole structure layer environmental load quantification and strengthen the comprehensive comparative analysis of domestic and foreign asphalt roads.The environmental load map of different regions provides practical basis for the construction of energy-saving and emission reduction roads in China from the aspects of material application,construction parameters,process path,etc.It has good theoretical significance and engineering application prospect.