Application of Wheel Tracking Device on the Evaluation of Moisture Damage of Porous Asphalt

• Main Authors: Jen-Hau Wu, 吳仁豪
• Other Authors: Ming-Jen Liu
• Format: Others
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/04505199440647217796

碩士 === 淡江大學 === 土木工程學系 === 90 === Porous asphalt possesses high air voids in order to drain the rainwater on the road surface effectively. However, porous asphalt pavements are susceptible to stripping and resulting in more serious damage with traffic loadings in hot and wet environment. Therefore, it is necessary for us to be aware of the stripping characteristics of the material in depth. Several wheel-tracking devices have already been developed in foreign countries for use to evaluate the moisture susceptibility of asphalt concrete. Because of the difficult of the acquisition of those devices, this research attempted to utilize the domestic wheel-tracking device to evaluate moisture damage of porous asphalt with pre-conditioning of specimens by immersion, so-called the pre-immersing treatment. In this research, immersing and testing schemes were selected as trial variables, and dense graded asphalt concrete (DGAC) was used for comparison basis. Besides, hydrated lime was employed as anti-stripping agent for porous asphalt. This research expected to find a distinguishable testing method out from the combinations of trial variables, probe into the effects of trial variables upon testing results, and compare the results of wheel tracking test with tradition stripping tests. After executing examinations of basic physical properties on asphalt cement and aggregate, asphalt concrete mix designs, performance tests and stripping tests (including Immersed Marshall Test and Immersed Cantabro Test), the wheel tracking test was utilized in this research to investigate moisture damage of porous asphalt. The immersing schemes were 24-hr and 48-hr, and the testing schemes were 1-hr and 6-hr. The parameters used to analyze testing results were percentage of stripping range (PSR), Dynamic Stability (DS), and the observed trends of deformation of specimens after 6-hr testing. Major results of this study were summarized as follows: 1.The results of wheel tracking test on pre-immersing specimens and traditional stripping tests all showed that porous asphalt was weaker than DGAC in resisting moisture damage, and hydrated lime could enhance the ability of porous asphalt in stripping resistance. However, there was no difference in the PSR value when specimens were immersed for 48-hr whether porous asphalt adding hydrated lime or not. In addition, the immersion of specimens seemed slash the DS value of porous asphalt, and the DS value of DGAC showed an unusual variation when immersing time increases. 2.The analysis method of deformation trend of the Hamburg Wheel Tracking Test was employed in this research. The results indicated that the analysis method of Hamburg Wheel Tracking Test is not applicable to the wheel-tracking test using pre-immersing specimens. It probably was due to the different mechanisms of these two wheel-tracking tests. The analysis method of Purdue Wheel Tracking Test that uses the number of passes producing a specific deformation seemed more rational for the wheel-tracking test using pre-immersing specimens. 3.Generally speaking, there were specific correlations between the result of wheel tracking test using pre-immersing specimens and that of traditional stripping tests. After comparing all the testing conditions, it was found that the PSR and DS value of specimens pre-immersed for 24-hr had better correlations with the results of traditional stripping tests.