Research On Compaction Properties Of Foamed Warm Mix Asphalt Mixtures

In recent years,as people pay more and more attention to environmental protection,the foamed warm mix asphalt(WMA)technologies have received a lot of attention due to the problems of high energy consumption,dust emission and harmful gas,pollution of the environment,and harm to the health of the builders in traditional hot mix asphalt.In addition,the early damage of asphalt pavement in China is serious.A large number of investigations and studies show that the main reason for the serious early damage is the poor compaction effect.Therefore,based on the indoor experiment,the following 5 aspects were mainly studied in this paper:Firstly,the basic properties of the raw material of the foamed WMA were tested by the experiment.The mix proportion design of the hot mix asphalt(HMA)was designed by the Marshall design method.And the mix proportion of asphalt mixture is verified by the pavement performance test.Secondly,foam asphalt was prepared by the water foaming technology,and the compaction performance parameters of the foamed WMA under different compaction temperatures were tested by the variable compaction temperature test.Based on the physical volume parameters and mechanical properties of Marshall specimen under different molding temperatures,the compaction temperature curve corresponding to the parameters of each compaction property have been established.According to the technical requirements of the current highway asphalt pavement construction technology specification,the compaction temperature range of the foamed WMA was obtained from the range median of VV,VFA,and the lower limit of the VMA,Marshall stability range.In addition,the influence of foaming water content and curing time on the compaction properties of foamed WMA were discussed.The optimum foaming water content of foamed warm mix asphalt was determined,and the effect of curing time on the splitting tensile properties of the mixture was revealed.Besides,the compaction height and the density of foamed WMA were studied by the test in different compaction times.The relationship between the key indexes of the compaction properties of the foamed WMA and the compaction times was analyzed.And the change rule of the compactness,W,Marshall stability and compaction times were revealed.Finally,based on the analysis of the compaction properties of foamed WMA,the pavement performance of the HMA and foamed WMA were compared.By comparison,the high temperature stability,low temperature anti-cracking performance and water stability of the mixture were respectively evaluated by the rutting test,bending test,immersion Marshall test and freeze-thaw splitting test.And the feasibility of the compaction control index of the foamed WMA proposed in this study was tested.