Application Study Of Bio-binder In Hot Mix Asphalt Mixture

With the increase of construction of new asphalt pavement and maintenance of existing asphalt pavement,the demand for asphalt is increasing.Bio-binder asphalt is non-petroleum based asphalt binder based on renewable resources(such as crop,urban waste and agriculture and forestry by-product).Bio-binder asphalt has the advantage of renewable,environment-friendly,resource production and good economic benefit.In recent years,bio-binder has become an alternative scheme to petroleum asphalt at home and abroad.But due to difference and diversity of bio-binder components,to a special bio-binder,whether it can be used in asphalt pavement construction needs to be studied.Original sample of bio-binder asphalt used in the study is made of corn stalk.At room temperature,it’s solid with no-fixed traits,with similar viscosity-temperature characteristic to petroleum asphalt.By studying on the heat aging index of original sample,treatment process is determined.Optimum temperature of pretreatment for original sample is 12℃,and the time is appropriate for 1h～2h.By using waste rubber powder,SBS and PPA to modify original sample,softening point is increased,PI index is decreased and ductility is decreased significantly.The modifying effect for original sample is not obvious.In order to investigate the applicability of bio-binder asphalt used in hot mix asphalt mixture,the bio-binder asphalt binder is mixed with 70#asphalt in different proportions(mass proportion on 70#asphalt respectively at 5%,10%and 15%)to make compound asphalt.By asphalt penetration test,softening point test,ductility test and rotary viscometer test,the basic properties and viscosity-temperature characteristic are studied.Through rutting test,low temperature bending test and freeze-thaw split test,the high temperature property,low temperature property and water stability of compound asphalt AC-13 asphalt mixture(bio-binder asphalt binder mixing amount is 10%)are studied.Preliminary test result shows that,the addition of plant based asphalt makes the penetration decreased somewhat,softening point increased and ductility decreased.But there’s no significant law of the three basic properties with plant based asphalt binder mixing amount.The viscosity-temperature characteristic of compound asphalt is similar to 70#asphalt,but viscosity value is decreased.Compared with 70#asphalt AC-13 asphalt mixture,the high temperature property,low temperature property and water stability of compound asphalt AC-13 asphalt mixture are all decreased.All the performance indexes meet technical specification requirements.High and low temperature bending creep test is experimented on compound asphalt AC-13 asphalt mixture(bio-binder asphalt binder mixing amount is 10%)and 70#asphalt AC-13 asphalt mixture.Combined with Burgers model,creep data is calculation fitted.Using the relationship between four parameters and high and low temperature property,comparative analysis results that high and low temperature property of compound asphalt both decreased,matching the mixture pavement performance test result.Orthogonal experiment design method is used to design bio-binder asphalt performance improvement experimentation.Modifier chooses waste rubber powder and SBS.The optimal scheme is that waste rubber powder content is 15%,SBS content is 2%and bio-binder content is 15%.