Research On The Smoke Suppression Effect And Road Performance Of Environmentally Friendly Asphalt Used In Tunnel Pavement

In recent years,with the acceleration of western development and the increase in urban road maintenance,the consumption of road asphalt has been increasing year by year.The issue of asphalt smoke has been a hot research topic in road engineering in recent years.Due to the fact that asphalt is obtained from petroleum residues through non-destructive distillation,several light hydrocarbons are prone to oxidation and volatilization at high temperatures,resulting in the generation of harmful volatile organic compounds(VOCs).VOCs have a negative impact on human health,and long-term exposure can lead to health problems such as decreased immunity,skin diseases,swelling of the brain,and difficulty breathing.In addition,VOCs will adhere to solid particles and invade soil and water through airflow,rainfall and other ways,causing longterm ecological environmental hazard.This article first conducts in-depth research on the principle of asphalt smoke release,methods to suppress VOCs emissions in asphalt,and the development of environmentally friendly modified asphalt.The selected modifiers(activated carbon,Al(OH)3,surfactant)are mixed and compounded,and environmentally friendly asphalt composite modifiers are developed.A self-designed simple asphalt smoke collection and detection device is used to real-time detect the VOCs emission process in the smoke during asphalt heating,Preliminary determination of the optimal combination.Research has shown that the environmentally friendly modified asphalt with the addition of C5+S3(5% activated carbon+3% surfactant)has the most significant inhibitory effect on VOCs.With the increase of activated carbon content,the penetration and ductility of environmentally friendly modified asphalt decrease,while the softening point increases with the increase of activated carbon content;With the increase of surfactant dosage,the penetration and ductility of environmentally friendly modified asphalt decrease;The softening point increases with the increase of surfactant dosage.Secondly,change the combination and dosage of modifiers to further explore the inhibitory effect of environmentally friendly modified asphalt on VOCs at different temperatures.A combination of headspace solid-phase microextraction and gas chromatography-mass spectrometry is used to extract and determine the specific components of VOCs in environmentally friendly modified asphalt with different modifier combinations,in order to explore the adsorption laws of different environmentally friendly modified asphalt on various components of VOCs.Research has shown that temperature has a significant impact on the VOCs emissions from asphalt.As temperature increases,the VOCs emissions from different environmentally friendly modified asphalt increase exponentially.Increasing the amount of activated carbon and surfactant can effectively improve the inhibitory effect on VOCs,but excessive addition may affect its inhibitory effect and instead increase the composition of VOCs in asphalt smoke.According to the characteristics of chemical components,the compounds in asphalt VOCs can be divided into three categories,namely aliphatic hydrocarbons,aromatic hydrocarbons,and hydrocarbon derivatives.Aliphatic hydrocarbons dominate the composition of VOCs.Activated carbon is more inclined to absorb fatty hydrocarbons and hydrocarbon derivatives in asphalt VOCs,while surfactants are more inclined to absorb aromatic substances.Then,frequency scanning tests,multiple stress repeated creep tests,and bending beam rheological tests were conducted on environmentally friendly modified asphalt prepared with different modifier dosages to test its rheological properties.Research has shown that the environmentally friendly modified asphalt with the addition of activated carbon and surfactants has improved its high-temperature deformation resistance,slightly weakened its low-temperature performance,and increased the opportunity for low-temperature cracking of environmentally friendly modified asphalt.Explored the effects of different modifier dosages on the road performance of environmentally friendly modified asphalt mixtures,including high-temperature rutting resistance,low-temperature cracking resistance,and water stability.Research has shown that the addition of activated carbon and surfactants significantly improves high-temperature stability,reduces low-temperature performance(in compliance with regulatory requirements),and improves water stability.Considering economic benefits,adding C5+S3 environmentally friendly modified asphalt has the best overall performance.Finally,based on the sealing conditions and ventilation conditions of highway tunnels,a simulation model of highway tunnels is established.Fluid dynamics theory(CFD)is used to study the diffusion and distribution characteristics of VOCs in environmentally friendly modified asphalt during the paving process in highway tunnels under the optimal modifier combination.Research has shown that at different heights of the tunnel,the release of VOCs from C5+S3environmentally friendly modified asphalt is much smaller than that of 70# base asphalt.As the height increases,the mass ratio of two types of asphalt VOCs in the air gradually decreases,showing a trend of first increasing and then decreasing over time.The diffusion law of asphalt smoke varies under different wind speeds.