The Study On Applicability Of Natural Gravel Aggregate In Asphalt Concrete Core Wall

In order to study and explore the applicability of natural gravel aggregate in asphalt concrete corewall,we study the adhesion ability between natural gravel aggregate with different lithology and pureasphalt through the adhesion test in the dissertation.We add different kinds of additive such ascement,hydrated lime powder,dolomite powder and tuff powder to the asphalt to make different kinds ofasphalt mastic.Also,we explore the measures which enhance the adhesion ability between aggregate andasphalt as well as their effects by the adhesion test between aggregate and asphalt mastic and the situationof Wuyi Reservoir Engineering in Xinjiang Province.We use orthogonal design method to make the designof mix proportion of natural gravel aggregate asphalt concrete,and select maximum particle size of coarseaggregate as19mm,choose grading index,asphalt content and filler content as3factors which have theirown3levels. We take marshall stability, marshall rhe, density and porosity as assessment index,choose thebest mixture ratio,and carry out the compression test,trabecular bending test,penetration test,water stabilitytest,marshall under vacuum test and freeze-thaw splitting test.We evaluate and analyze the applicability ofnatural gravel aggregate in asphalt concrete core wall.Additionally,we discuss several questions aboutadhesion tests and water stability tests in current hydraulic asphalt concrete test regulations.Moreover,wepropose improved suggestions according to the result of the test. The main conclusions are as follows.（1） The natural gravel aggregate in Wuyi Reservoir consists of three kinds of rock.The tuff takes75%of all the aggregate, showing neutral, while granite takes17%showing acidity, and andesite takes8%showing acidic.（2） In spite of dipping boiling3minutes stipulated in the current hydraulic asphalt concrete testprocedures,the test is still unable to distinguish the differences between acidic aggregate with alkalineaggregate on adhesion.Only after we extend the dipping boiling time more than9minutes can it appearsthat the adhesion ability of different kinds of natural gravel aggregate and asphalt became obviouslydifferent.So,we suggest that we should entend the dipping boling time,and proposed new standard which fitthe experiment extended the dipping boiling time.（3） The adhesion of aggregate and asphalt is not only related to the aggregate of lithology,but alsothe filler in the asphalt concrete.However, the improved effect on lithology aggregate adhesion ability isdifferent according to different types of alkaline additive.For the natural gravel aggregate of WuyiReservoirs,to add cement to asphalt is the best improved effect on adhesion ability.（4） The mixture ratio of natural gravel asphalt concrete in Wuyi Reservoir is grading index of0.36,asphalt content of6.4%, and filler content of11%,the cement is both the filler and the improvedmeasures of aggregate and asphalt adhesion.A series of performance test of natural gravel aggregate asphaltconcrete shows that cement has significant improvement to the adhesion between natural gravel aggregateand asphalt as filler.The natural gravel aggregate can meet the requirements of design specifications,and itcan reach the ability of dolomite aggregate asphalt concrete.（5）The current water stability test can’t give an accurate evaluation to the water stability hydraulicasphalt concrete.We suggest that we should carry out further experimental study and explore other auxiliarymethods to give an comprehensive assessment of water stability of hydraulic asphalt concrete.