--ISAP Graduate Student Research Directory
Student
Qing Lu
Thesis Title
Investigation of Conditions for Moisture Damage in Asphalt Concrete and Appropriate Laboratory Test Methods
Abstract
(Summary, conclusions, key achievements)
Moisture damage is a complex distress phenomenon in asphalt pavements. Both field and laboratory investigation were performed in this study to:
(1) Estimate the effect of different variables on the occurrence and severity of moisture damage and to determine major factors associated with moisture damage in the field;
(2) Evaluate the effectiveness of the Hamburg wheel tracking device test to determine moisture sensitivity of asphalt mixes and to predict field performance;
(3) Develop and evaluate dynamic loading involved test procedures for determining moisture sensitivity of asphalt mixes;
(4) Evaluate the effectiveness, especially the long-term effectiveness, of hydrated lime and liquid anti-stripping agents.
The field investigation shows that about ten percent of pavements with previously undocumented performance in the survey list experienced significant moisture damage. Moisture exists in almost every pavement, with a content ranging from zero to three percent. Statistical analysis shows that air-void content, cumulative rainfall, pavement age, and mix type are significant at the 90 percent confidence level in affecting moisture damage. The effect of variation in air-void content and binder content on the moisture sensitivity of asphalt mixes was studied by the flexural beam fatigue test. Results showed that a reduction in the binder content or an increase in the air-void content will significantly reduce the moisture resistance, in terms of fatigue life, of a good performance mix.
The correlation between the Hamburg wheel tracking device (HWTD) test results and field performance seems acceptable except that the test procedure may fail mixes that perform well in the field and, in a very few cases, give false positive results.
A new approach of testing was explored in this study using a fatigue-based test procedure for evaluating moisture sensitivity. An extension of the test procedure for use in pavement design was also discussed. It was found that the test procedure determined in this study can distinguish mixes with different moisture sensitivities, and give a ranking of mixes consistent with prior field experience. The variance of the fatigue test results, however, is relatively large.
Laboratory tests show that both the hydrated lime and liquid antistripping agents are effective in improving the moisture resistance of asphalt mixes after one-year moisture conditioning.
Starting Date:
8/1/2001
Final Completion:
12/15/2005
University
(or institution)
University of California, Berkeley, USA website
Chair, Civil Engineering
John T. Harvey website
e-mail: jtharvey@ucdavis.edu
Student
Qing Lu
email: qlu@ucdavis.edu
Academic Achievements
(degree, grants, publications, etc.)
M.E.: Southeast University, China, 4/2000, B.E. Southeast University, China, 7/2000:
1. Lu, Q., Harvey, J. Evaluation of Hamburg Wheel Tracking Device Test by Laboratory and Field Performance Data. Accepted for publication in the Journal of the Transportation Research Board. 2006.
2. Lu, Q., Harvey, J. Long-term Effectiveness of Antistripping Additives: Laboratory Evaluation. Accepted for publication in the Journal of the Transportation Research Board. 2006.
Permission to post on ISAP website
(Members only)
Yes
Date:
9/5/2006