The Mechanism Of Water Injection WARM Recycling Of Reclaimed Asphalt Pavement

The water injection foaming warm mix asphalt(WMA)technology is a new technology that is green and sustainable,which has achieved a more extensive application in the United States and other developed countries.Although this technology has been introduced into China with some indoor researches and field projects for some years,there is still a technology need to be further studied and developed.The purpose of the project is to improve the quality and stability of water-foaming WMA containing reclaimed asphalt pavement(RAP)and increase the recycling rate of RAP by understanding the influence of the factors on the properties of water injection WMA recycled asphalt mixtures.Firstly,study effect of mixing condition,sequence and curing time on the properties of the recycled asphalt mixtures produced by using three different dosage of RAP,three pre-heating temperatures for RAP before mix,three aggregate heating temperatures and three mixing pot temperatures.There are three mixing methods: 1)mix new aggregate,RAP and foaming asphalt at the same time;2)mix new material and RAP first,then mix with foaming asphalt;3)mix RAP and foaming asphalt first,then add new material for mixing.After mixing,curing times were controlled for different times of 1-45 days.Secondly,high temperature performance of rutting resistance was carried out on all the mixtures.Finally,the asphalt mixture in different curing times were extracted and the extracted asphalt binders were tested by DSR,AFM test and FTIR infrared spectrum tests.The conclusions of this study were drawn as follows:1)in the mixing temperature of130 ℃,a 120 ℃ of pre-heating temperature of RAP,a 150 ℃ of new aggregate heating temperature produced the best performance properties of the mixtures;2)a mixing process of new aggregate and RAP first,and then foamed asphalt mixing again,was proved the best;3)with the increase of curing time,the water injection WMA mixtures performed increasingly better.