Research On Evaluation Method For Self-healing Capability Of Asphalt Mixtures

It has been confirmed that asphalt mixture is a self-healing material which has abuilt-in ability to (partially) recover material strength, stiffness and to prolong fatiguelife during its service life. Researchers in road engineering have been paying highattention to this phenomenon in faith that the self-healing capability is able to resist tothe fatigue cracking. Though great progress has been made through diligent work,there are still some crucial questions existing: what the self-healing phenomenon is;how to measure it effectively and efficiently and how to upgrade it if possible. Inorder to answer the second question, this research focuses on the influence factors,experimental evaluation model and fuzzy comprehensive evaluation method ofself-healing capability, as follows:(1) The main indicators and relevant effects have been summarized on the basisof a comprehensive study on the influence factors of self-healing capability.(2) A beam on elastic foundation (BOEF) test was introduced to investigate theself-healing phenomenon of asphalt mixtures with a notched asphalt concrete beamfully glued on a low modulus rubber foundation. The three-point flexural strength wasused as a major indicator of healing for asphalt mixtures in this experimentalevaluation model, and a calculation method was proposed for the notched asphaltconcrete beam based on the finite element analysis and experimental data. Finally, acase study verifies that this experimental evaluation model can be well used for studyon the self-healing mechanism, affecting indicators and self-healing capability ofasphalt mixtures.(3) On the basis of a general study on the influence factors of self-healingcapability, the paper proposed an evaluation indicator system for the self-healingcapability of asphalt mixtures, and established a numerical method to describe theirproperties. Four types of score functions with16mathematical expressions were setup to describe the properties of continuous indicators, and empirical methods wereused to deal with dispersion indicators’ properties. Then, based on two types ofevaluation principles, successive evaluation and common evaluation principles, andthe improved analysis hierarchy process method, two fuzzy comprehensive evaluationmethods were introduced to evaluate the self-healing capability of asphalt mixtures.The analysis results of an engineering example using the proposed method verify the feasibility and effectiveness of the two fuzzy comprehensive evaluations forself-healing capability of asphalt mixtures.