Effects Of Buton Rock Asphalt Content On Performance Of Modified Asphalt Mixture

In order to investigate the effects of Buton rock asphalt content on performance of modified asphalt mixture,Penetration 70 Grade A petroleum asphalt was used as base asphalt for preparing modified asphalt binder containing rock asphalt up to 40%of the base asphalt.Limestone aggregate was used in designing AC-20 C asphalt mixture of various percentages of rock asphalt using Marshall method,performance tests and test results analyses on modified asphalt mixture with different percentages of Buton rock asphalt were then carried out,All the efforts offer guidance for the application of Buton rock asphalt modified asphalt mixture in engineering projects.Firstly,designs of AC-20 C modified asphalt mixture with different contents of rock asphalt using rotation-compaction method and Marshall method were conducted at the stage of mix design.Test results and analyses indicate that the optimum asphalt aggregate ratios out of rotation-compaction method compared to Marshall method are generally a bit smaller.Because our country usually use the Marshall method,the optimum asphalt aggregate ratios out of Marshall method were chosen to do further tests.Secondly,Laboratory tests were carried out for determining properties of the asphalt mixture modified with various percentages of Buton rock asphalt.These properties include Marshall properties from Marshall test,dynamic stability from rutting test,retained Marshall stability from immersion Marshall test and tensile strength ratio from freeze-thaw indirect tension test,failure strain from low temperature flexural test,and water permeability coefficient from permeability test.Test results and analyses indicate that with increasing rock asphalt percentage,the high temperature rutting resistance,moisture damage resistance,and the permeability resistance of the modified asphalt mixture improve gradually to varying degrees.On the other hand,with increasing rock asphalt percentage,the low temperature cracking resistance of the modified asphalt mixture slightly improves to a peak value and then falls back slightly,but the overall increase is not large.The recommended maximum percentage of Buton rock asphalt for paving asphalt mixture is 30% of the base asphalt.Finally,pavement structure design parameters of asphalt mixture modified with various percentages of Buton rock asphalt were tested.Test results and analysesindicate that with increasing percentage of rock asphalt,compressive resilient moduli from compression tests at 20℃ and 15℃,and tensile strength from indirect tension test at 15℃ increase gradually to varying degrees.At the same time,asphalt mixture modified with various percentages of Buton rock asphalt pavement structure was calculated.results and analyses indicate that with increasing percentage of rock asphalt,maximum cumulative equivalent axle load and ultimate axle load increase gradually.