Moisture damage in asphalt mixtures is a complex phenomenon that involves mechanical, chemical, physical and thermodynamic processes. This damage contributes significantly to the premature deterioration of asphalt pavements, which leads to extra cost in highway maintenance and vehicle operations. One key mechanism of how moisture reaches the asphalt-aggregate interface is by its permeation or diffusion through the asphalt binder or mastic. Different techniques are available for diffusion coefficient measurement of a wide variety of polymersolvent systems. For the asphalt-water system studied, the focus is on two techniques: (i) Fourier Transform Infrared (FTIR)-Attenuated Total Reflectance (ATR) spectrometry and (ii) Gravimetric Sorption Measurements. In the FTIR-ATR experiments, asphalt binders are under investigation. Water shows strong absorption in the infrared region and the FTIR-ATR technique has the ability to monitor both the kinetics of moisture ingress as well as any chemical changes occurring during the test. The changes in concentration can be directly related to change in the absorbance measured during the experiment. The hysteresis of water diffusion in asphalt binders is also monitored through this technique. In the gravimetric sorption experiments, cylindrical Fine Aggregate Mixtures (FAM) were investigated. The gravimetric techniques, which directly follow mass change with time, are among the most used techniques probably because of their simplicity. In this experiment, the Saturated Surface-Dry (SSD) weight of FAM samples at room temperature and at 100 degrees F is monitored until it reaches the equilibrium. The measurements of: (i) water uptake and (ii) the diffusion coefficient were made at both temperatures. A dual mode diffusion model was shown to better represent the diffusion of water through asphalt binders. The rate of moisture diffusion in asphalt binders was proved to be dependent on the history of exposure of the asphalt binder to the moisture. Moisture uptake and diffusivity of water through FAM is dependent on the type of aggregate and asphalt binder used to prepare the FAM.

Fatigue cracking is one of the fundamental distresses that occur in the life of a Hot Mix Asphalt Concrete (HMAC) pavement. This load induced distress leads to structural collapse of the entire pavement ultimately and can only be remedied by rehabilitation. There is the need, therefore, for a total understanding of the phenomenon to be able to counter its occurrence. The fatigue resistance of hot mix asphalt concrete (HMAC) has been estimated using approaches ranging from empirical methods to mechanistic-empirical methods to purely mechanistic methods. A continuum mechanics based approach called the Calibrated Mechanistic with Surface Energy (CMSE) measurements was developed at Texas A&M University and recommended after comparison with other approaches in predicting fatigue lives of two Texas HMAC mixtures. The CMSE approach which includes fundamental material properties such as fracture, aging, healing, and anisotropy has been shown to effectively model the parameters that affect the performance of HMAC pavements exposed to repetitive traffic loads. Polymer modified asphalt (PMA) improves pavement performance by providing additional resistance to the primary distresses in flexible pavements, including permanent deformation or rutting, thermal cracking, and fatigue cracking. In this research, the CMSE approach was utilized to estimate the fatigue resistance of HMAC fabricated with asphalts modified with Styrene-butadiene-Styrene (SBS) co-block polymer. These HMAC mixtures were fabricated from materials used on three different road sections in Texas and one test pavement in Minnesota. The CMSE approach was validated as an effective approach for estimating the fatigue resistance of HMAC mixtures with PMA. The effect of oxidative aging on the fatigue resistance of the HMAC mixtures was also verified. Oxidative aging of the mixtures resulted in a corresponding decrease in mixture fatigue resistance. In addition, for two HMAC mixtures with the same binder content and aggregate gradation, the mixture with the softer of the two Performance Grade (PG) binders exhibited greater fatigue resistance. The use of the Utility Theory revealed the possible effects of aggregate geometric properties on the HMAC mixture properties and consequently on their fatigue resistance.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 79 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-54).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 156-172). Available also in a digital version from Dissertation Abstracts.

This research project concentrated on determining whether or not a correlation existed between laboratory aggregate tests and observed aggregate field performance. For this purpose, aggregate samples were collected from the majority of the U.S. states as well as several Canadian provinces and subjected to a variety of strength, soundness, and intrinsic particle property tests. Additionally, performance data on the aggregates was obtained by contacting multiple DOT's where aggregates were in use in several categories - hot-mix asphalt, portland cement concrete, base course, and open-graded friction course. Numerical and qualitative analyses were performed to evaluate the success of separating good performers from fair and poor performers using the micro-Deval test alone as well as the micro-Deval test combined with another test. Furthermore, attempts were made to determine if a correlation exists between any two tests.

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Project Completion Report / OWRT Project No. A-059-ARIZ / Development of Asphalt Cushioned Plastic and Plastic Reinforced Asphalt Membranes for Seepage Control / Agreement No. 14-31-0001-5003 / Project Dates: July 1974-June 1975. / This project was concerned with laboratory equipment development, laboratory testing, construction equipment development and field investigation of the APAC (Asphalt-Plastic-Asphalt-Chip-Coated) water seepage barrier. The laboratory equipment that was designed and fabricated for the project included hydrostatic testing vessels, slope stability apparatus, and tensile testing grips. Three testing methods were utilized and evaluated in the APAC investigation. The first test method evaluated the hydrostatic puncture resistance of the asphalt-polyethylene combination. This test confirmed the hypothesis that the asphalt effectively increases the puncture resistance of the APAC membrane over that of plain polyethylene. The second test investigated the slope stability of a protective APAC chip seal. It was found that a typical 3/8 in. (9.5 mm) cover aggregate remained stable on constructed slopes of 3:1 and 4:1 and that the 2:1 slope remained stable up to a surface temperature of 1220F (500C). The third test method evaluated adhesive materials and indicated that Presstite mastic was the best suited adhesive for sealing polyethylene overlaps. Subsequent field investigations resulted in equipment development that increased construction efficiency in the installation of the APAC membrane. Actual completed field installations were evaluated and further recommendations are included.

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