Biochar is currently applied in many low-impact development measures,such as biofilters and filter strips.However,its application in permeable pavement is limited.Due to the wide range of raw material sources,biochar ...Biochar is currently applied in many low-impact development measures,such as biofilters and filter strips.However,its application in permeable pavement is limited.Due to the wide range of raw material sources,biochar may also contain nutrients and heavy metals.Whether its leachate will cause contamination during application remains unknown.Based on the static leachate contamination test,this study first evaluated the leachate contamination risks of three types of biochar and porous asphalt mixture(PA)with three biochar fillers.Through the pavement infiltration test,the purification performance of PA with biochar fillers and filter layers was further analysed.The results show that biochar contains nitrogen and phosphorus,and the leaching contamination of coconut shell is the most obvious;when the biochar is applied as a filler in PA,the leaching contamination decreases,while the pollutant purification performance is not obvious;when 3−5 mm rice straw biochar is used as a filter layer,the removal rate of total suspended solids can be 100%,but it is accompanied by more serious nitrogen and phosphorus leaching,and the greater the thickness,the more serious the degree of leaching.Deionized water cleaning can remove the phosphates contained in biochar,but have little effect on nitrogen.Therefore,before the application of biochar,cleaning measures should be taken to minimize its leaching contamination.展开更多
Porous polyurethane concrete(PPUC)is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete.However,studies of the mechanical properties of PPUC are st...Porous polyurethane concrete(PPUC)is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete.However,studies of the mechanical properties of PPUC are still insufficient.In this study,the comprehensive mechanical properties and water stability of PPUC with different gradations and polyurethane dosages were investigated,and its water damage mechanism was preliminarily explored.The results show that the flexural strength and Marshall stability of PPUC can more easily reach the index in the standards of porous cement concrete or porous asphalt,while the compressive strength and abrasion resistance are the weak points of its mechanical properties and need to be further optimized.The mechanical properties and water stability of PPUC were effectively improved by increasing the polyurethane dosage and using continuously graded aggregates.PPUC is more susceptible to water damage because water reacts with the residual isocyanate groups within the polyurethane film to generate carbon dioxide gas,which reduces the cohesion and adhesion performance of polyurethane film.This study provides a comprehensive understanding of the mechanical properties of PPUC and an initial insight into the mechanism of water damage.展开更多
Because of abundant reserves and renewable and environmentally friendly properties,the utilization of woody biomass waste in road engineering can alleviate the shortage of fossil fuels and carbon emissions so as to mi...Because of abundant reserves and renewable and environmentally friendly properties,the utilization of woody biomass waste in road engineering can alleviate the shortage of fossil fuels and carbon emissions so as to mitigate global climate change and achieve sustainable development of road engineering.This paper synthesizes the state of the art about the strategies of applying five kinds of resources derived from waste woody biomass,including biochar,bio-oil,lignin,wood ash and nanocellulose to road construction.Based on the characteristics analysis of the five materials,it can be concluded that biochar can comprehensively improve the road performance of asphalt and its mixtures,and has the potential of runoff purification;bio-oil can soften asphalt and improve its lowtemperature performance,but has negative effects on high-temperature performance;lignin increases the asphalt ageing resistance and can be used as a regenerant,and will improve the overall performance of asphalt mixtures if combined with other modifiers;wood ash can increase subgrade bearing capacity and bring significant environmental benefits;nanocellulose improves the strength of cement mortar,but there is a lack of research on its effects on performance of pavement materials and the interaction mechanism;the lifecycle environmental and economic assessment of woody biomass-modified road materials is not comprehensive.Moreover,prospects were also summarized to show the opportunities for future study,such as the establishment of a database for biomass.This review provides useful insights for the utilization of woody biomass as road materials to achieve waste management and sustainable development.展开更多
基金supported by a grant from the Fundamen-tal Research Funds for the Central Universities of China (Grant No.22120210027).
文摘Biochar is currently applied in many low-impact development measures,such as biofilters and filter strips.However,its application in permeable pavement is limited.Due to the wide range of raw material sources,biochar may also contain nutrients and heavy metals.Whether its leachate will cause contamination during application remains unknown.Based on the static leachate contamination test,this study first evaluated the leachate contamination risks of three types of biochar and porous asphalt mixture(PA)with three biochar fillers.Through the pavement infiltration test,the purification performance of PA with biochar fillers and filter layers was further analysed.The results show that biochar contains nitrogen and phosphorus,and the leaching contamination of coconut shell is the most obvious;when the biochar is applied as a filler in PA,the leaching contamination decreases,while the pollutant purification performance is not obvious;when 3−5 mm rice straw biochar is used as a filter layer,the removal rate of total suspended solids can be 100%,but it is accompanied by more serious nitrogen and phosphorus leaching,and the greater the thickness,the more serious the degree of leaching.Deionized water cleaning can remove the phosphates contained in biochar,but have little effect on nitrogen.Therefore,before the application of biochar,cleaning measures should be taken to minimize its leaching contamination.
基金supported by the Fundamental Research Funds for the Central Universities (No.22120210027).
文摘Porous polyurethane concrete(PPUC)is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete.However,studies of the mechanical properties of PPUC are still insufficient.In this study,the comprehensive mechanical properties and water stability of PPUC with different gradations and polyurethane dosages were investigated,and its water damage mechanism was preliminarily explored.The results show that the flexural strength and Marshall stability of PPUC can more easily reach the index in the standards of porous cement concrete or porous asphalt,while the compressive strength and abrasion resistance are the weak points of its mechanical properties and need to be further optimized.The mechanical properties and water stability of PPUC were effectively improved by increasing the polyurethane dosage and using continuously graded aggregates.PPUC is more susceptible to water damage because water reacts with the residual isocyanate groups within the polyurethane film to generate carbon dioxide gas,which reduces the cohesion and adhesion performance of polyurethane film.This study provides a comprehensive understanding of the mechanical properties of PPUC and an initial insight into the mechanism of water damage.
基金supported by the National Key Research and Development Program of China (No.2018YFB1600100)the Fundamental Research Funds for the Central Universities (No.22120210027).
文摘Because of abundant reserves and renewable and environmentally friendly properties,the utilization of woody biomass waste in road engineering can alleviate the shortage of fossil fuels and carbon emissions so as to mitigate global climate change and achieve sustainable development of road engineering.This paper synthesizes the state of the art about the strategies of applying five kinds of resources derived from waste woody biomass,including biochar,bio-oil,lignin,wood ash and nanocellulose to road construction.Based on the characteristics analysis of the five materials,it can be concluded that biochar can comprehensively improve the road performance of asphalt and its mixtures,and has the potential of runoff purification;bio-oil can soften asphalt and improve its lowtemperature performance,but has negative effects on high-temperature performance;lignin increases the asphalt ageing resistance and can be used as a regenerant,and will improve the overall performance of asphalt mixtures if combined with other modifiers;wood ash can increase subgrade bearing capacity and bring significant environmental benefits;nanocellulose improves the strength of cement mortar,but there is a lack of research on its effects on performance of pavement materials and the interaction mechanism;the lifecycle environmental and economic assessment of woody biomass-modified road materials is not comprehensive.Moreover,prospects were also summarized to show the opportunities for future study,such as the establishment of a database for biomass.This review provides useful insights for the utilization of woody biomass as road materials to achieve waste management and sustainable development.
