Experimental simulation for moisture damage of saturated asphalt mixture and evolution of mixture’s pore water pressure, accumulative strain

Abstract

Moisture damage has significant impact on pavement’s performance and service life, researching this kind of distress’ mechanical mechanism, experimental simulation protocol or theoretical analysis method continues to be the research that should be conducted in depth for pavement researchers. But, due to the complexity of this distress’ influencing factors, there is still not a satisfactory research result by far, particularly for its experimental simulation test, the current research lack of a satisfactory apparatus or protocol that can simulate asphalt mixture’s moisture damage in lab. So then, this paper, basing on a fully mechanical analysis in advance for asphalt pavement’s moisture damage, develops an experimental apparatus being capability to simulate and investigate asphalt mixture’s moisture damage in lab by improving a dynamic triaxial tester, then utilizes this improved triaxial tester investigate moisture damage of asphalt mixture with different air void percent or applied by different confining pressure, and acquires these mixture’s characteristics regarding their pore water pressure evolution, strain cumulation, specimen deformation as well as their influencing factors, then classifies these test results into three types according to their characteristics. The test results demonstrate, this developed apparatus can comparatively satisfactorily simulate mixture’s moisture damage phenomena in lab, its simulation test results are close to field investigation results, and air void percent, confining pressure and loading frequency are the principal factors that have significant impact on mixture’s moisture damage test results. For the specimen with lower air void percent or under a higher confining pressure, their test results are primarily type 1, whose pore water pressure and cumulative strain are relatively low, deformation are pure compression. Whereas, for the specimen with larger air void percent or applied by higher confining pressure, their pore water pressure and cumulative strain are usually larger, specimen are generally observed with stripping or cracking in the end of test, even some are found with diagonal cracks, these characteristics are classified as type 3. As for type 2, their test results are primarily between that of type 1 and type 3, their pore water pressure, cumulative strain are relatively large, yet specimen’s deformation mainly attribute to compression, and only swelling in radial direction or slight stripping are found with specimens.