Research On Application Of Broken Gravel In Asphalt Layer

Gravel is a rock or mineral particle,size greater than 2 mm,with the characteristics of high strength and corrosion resistance,which has been widely used in the construction engineering.In this paper,the gravel is edgeless river pebbles which has been transported by the river for a long time.Gravel used in base and subbase,more less in the application of surface in the asphalt road.However,it has some limitations in terms of road.In the highway industry,it is used for the base and the grass roots,what is used for asphalt surface layer is relatively rare.If the gravel can be used in the asphalt surface layer that can not only make the road construction cost savings,but also can ease the growing tension of the stone resources and protects the environment to a certain extent.Firstly,the physical properties of the broken gravel are be tested,the result shows that the broken gravel of different color in terms of physical properties conform to the middle and lower layer material specification requirements of high grade highway;Comparing gradation for AC-20 C,coarse aggregate all broken gravel,fine aggregate of limestone and breakage of gravel asphalt mixture performance of the two groups,the result shows that using the alkaline limestone fine aggregate,to a certain extent,can improve the water stability and high temperature performance of broken gravel mixture.The Impact on the low temperature is smaller.Secondly,counting the ratio of smooth surface particles in aggregate and using the Improved water immersion method to study the influences of crushed gravel which has 30%smooth surface on the adhesion of mineral aggregate and asphalt.For the problem that electron microscopy scanning found lower gravel break up surface roughness,Freeze-thaw splitting test to cement and anti-stripping agent dosage,respectively with asphalt content of0.4% and the original mineral powder of 50%,to improve broken gravel and asphalt adhesion;Through studying different compaction times different void fraction of freeze-thaw splitting test results,the effects of improved broken gravel air voids of asphalt mixture under 4.5%when the water damage resistance of the effect is better;Replacing the limestone fine aggregate with the broken gravel fine aggregate,studying broken gravel on water stability of asphalt mixture to improve effect,the results show that(50% of cement + 0.4% ofantistripping agent)> 50% of cement > 0.4% of antistripping agent.Finally,under the condition of using the crushed gravel to replace the limestone fine aggregate,researching on the influences of three kinds of improvement measures to broken gravel asphalt mixture performance.And on the performance of high temperature rutting test dynamic stability and permanent deformation is studied,the results show that mixture adding cement has good shear strength;And three-point bending,indirect tensile test are be used to study the low temperature performance,the results show that in the aspect of flexural tensile strength and ultimate strain adding cement is better than anti-stripping agent.Adopting thirds point test to study fatigue performance,the results show that adding cement can increase the fatigue life and the ultimate bending tensile strain improvement measures than not add mix improved 19.3%.