Evaluation of anti-reflective crack resistance based on the UFAC stress-absorbing layer
Objectives To address the issue of reflective cracking in"white and black"pavement technol-ogy,this paper proposes an optimized design for a skeleton-dense UFAC stress-absorbing layer.This de-sign,based on the CAVF method and the concept of rich asphalt,aims to overcome the shortcomings of the commonly used dense-graded super flexible asphalt concrete(SFAC)stress-absorbing layer,which tends to exhibit significant deformation and adversely affect the overlaid asphalt layer.Methods The finite element method using ABAQUS was employed to conduct a stress analysis of the"white and black"pave-ment structure.Additionally,the reflective cracking resistance of the materials and structure was evaluated through accelerated loading tests,impact toughness tests,and splitting tests.Results Under heavy load con-ditions,the vertical displacement difference between the UFAC stress-absorbing layer and the SFAC stress-absorbing layer is 5.93×10-2 mm.Consequently,the vertical compressive stress(σy),maximum principal stress(σmax),and maximum shear stress(τ12)at the bottom of the asphalt overlay are reduced by 24％,32.3％,and 27.7％,respectively.In cases where the pavement has severe or typical voids,the fatigue crack resistance of the asphalt overlay structures based on the UFAC stress-absorbing layer is improved by 48％and 36％,respectively,compared to the GAC overlay pavement structures.Additionally,compared to the traditional dense-graded sand-asphalt AC-5 stress-absorbing layer,the skeleton-dense UFAC-5 stress-absorbing layer exhibits a 60.8％increase in impact toughness and a 16.8％improvement in splitting tensile strength.Conclusions The significant deformation characteristics of SFAC stress-absorbing layers can ad-versely affect the overlaid asphalt layer,leading to reflective cracking and premature pavement damage.The asphalt overlay technology based on the UFAC stress-absorbing layer addresses these issues by increasing the thickness of the conventional modified asphalt film to ensure the necessary fatigue tensile strength.Ad-ditionally,it employs a skeleton-dense gradation to significantly enhance the interlocking capacity and internal friction of the aggregate,reducing interlayer structural deformation.This effectively mitigates the occur-rence and progression of reflective cracks in the asphalt overlay.
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