Studying Of The Influence Of The Maximum Size Of Coarse Aggregate On The Pouring Asphalt Concrete

To explore and study on the Performance effect of pouring asphalt concrete which is made up of thenatural gravel as coarse and fine aggregates and change the maximum size of coarse aggregate from the19mm to31.5mm. Now uses the uniform orthogonal designs method to the two largest aggregate diameterfor asphalt concrete mixture ratio design separately. Choose the above two groups of mix design forcompression、water stability test、operating viscosity、separating degree and static triaxial test.Analysisand discuss the two groups of different maximal particle dameter on the effect of asphalt concretestress-strain relationship; Combined with one project in xinjiang, use the Finite element analysis methodon the static triaxial test results,now summarized the main test results as fllows:(1)It can be divided into two groups according to the different maximum particle size of coarseaggregate.The first group which the maximum aggregate diameter is31.5mm is the key for this text,and itsgrading index is from0.38to0.42, asphalt usage from7%~8%. The second of19mm which is standard andis commonly used for project,and its grading index is from0.30to0.36, asphalt usagefrom9%~10%.Through the uniform orthogonal designs method to the largest aggregate diameter for asphaltconcrete mixture ratio design separately,selected a more optimal mixture ratio design. When the maximumsize of coarse aggregate is31.5mm, Mineral aggregate gradation index n=0.42, packing materials is14%,asphalt content is7.5%. When the maximum size of coarse aggregate is19mm, mineral aggregate gradationindex n=0.33, packing materials is10%, asphalt content is9%.(2)The asphalt content of aggregate maximum diameter of31.5mm is more smaller than thespecifications of the recommended range(asphalt content of9%~13%). Asphalt usage transformed intoasphalt content,theasphalt content is only6.98%, asphalt content is between the roller compacted asphaltconcrete and pouring asphalt concrete. And the density of aggregate maximum particle size of31.5mm iscloser to the density of roller compacted asphalt concrete.(3)For the selected two groupsof the mixture ratio,(maximum particle size of19mm is number8mixture ratio, maximum particle size of31.5mm is number3mixture ratio),From the complex text,we canfind: the stability of the third mixture ratio is bigger than the eighth mixture ratio20%.Compared Theasphalt content of aggregate maximum diameter of31.5mm of pouring asphalt concrete with The asphaltcontent of aggregate maximum diameter of19mm of roller compacted asphalt concrete, The asphaltcontent of aggregate maximum diameter of31.5mm of pouring asphalt concrete’s stability is smaller thanthe asphalt content of aggregate maximum diameter of19mm of roller compacted asphalt concrete21.5%,and the flow value is2.5times than the asphalt content of aggregate maximum diameter of19mmof roller compacted asphalt concrete.(4) Two groups of different mixture ratio take the performance test of pouring asphalt concrete.Toensure the optimization of the mix proportion could meet the design requirement.The asphalt content ofaggregate maximum diameter of31.5mm’s Compressive Strength is much bigger,and the compressionmodulus is also bigger,but deformation is much smaller.from this we can see the asphalt concrete materialsis much harder.The asphalt content of aggregate maximum diameter of19mm’s material is more soft, thecompressive strength is much smaller, the compression modulus is much smaller, but the deformation isbig.(5) The water stability is satisfied with the design requirements and consistent with theexistedresults,the more use of asphalt,the lower asphalt concrete compressive strength is and the biggerwater stability coefficient is. The Construction fluidity could meet the design requirements and resolution issatisfied with the design requirements.(6) The asphalt content of aggregate maximum diameter of31.5mm of pouring asphalt concrete andthe asphalt content of aggregate maximum diameter of19mm of roller compacted asphalt ‘sconcrete,stress-strain curve is accord with hyperbolic model,compared with it, the asphalt content ofaggregate maximum diameter of19mm is more accord with hyperbolic model. In four different sizes ofconfining pressure, the asphalt content of aggregate maximum diameter of31.5mm’s maximum partialstress is bigger than the asphalt content of aggregate maximum diameter of19mm.(7)According to the finite element analysis, vertical displacement and stress level and ratio ofprincipal stress distribution is basically reasonable.So the asphalt concrete mixture can meet theengineering works and both maximum particle size of aggregate can be used in engineering.