Effect of Water Conditioning for Extended Periods on the Properties of Asphalt Binders

Abstract

Selecting materials with a low susceptibility to moisture damage (i.e., stripping) is critical to guarantee the performance of asphalt pavements. Stripping in the asphalt mix can accelerate damage and consequently reduce pavement life. Most current research on moisture damage considers the effect of water on the mastic, the aggregate, and the adhesive bond between the aggregate and the binder. However, limited research has been conducted to determine the effect of extended water exposure on the properties of asphalt binders. This study investigated the influence of extensive water exposure on the stripping potential of asphalt binders by measuring the rheological properties, bond strength, and wettability of a Colombian binder before and after immersion. Thin films (2-mm height) of asphalt were immersed in water for 3, 6, and 9 months, and comparisons were made between the experimental results of unconditioned and conditioned binders. Master curves for complex modulus and phase angle were obtained by using a frequency sweep test in a dynamic shear rheometer. The bond strength between the binder and aggregates was measured with the recently developed binder bond strength test. The wettability potential of the conditioned and unconditioned binder was estimated by using the sessile drop method, and dynamic modulus testing of mixes prepared with the unconditioned and conditioned binder was conducted. Experimental results showed significant changes in the properties of the binder after 9 months of water conditioning. Further, dynamic modulus of the mixes prepared with the binder conditioned for 9 months was significantly higher than the modulus of the unconditioned mix.

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References

Caro

, Masad

E. A.

, and Bhasin

Moisture Susceptibility of Asphalt Mixtures, Part 1: Mechanisms. International Journal of Pavement Engineering, Vol. 9, No. 2, 2008, pp. 81–98.

Kigundu

, and Roberts

F. L.

Stripping in HMA Mixtures: State-of-the-Art and Critical Review of Test Methods. NCAT Report 88-02. National Center for Asphalt Technology, Auburn University, Auburn, Ala., 1988.

Rice

Relationship of Aggregate Characteristics to the Effect of Water on Bituminous Pavement Mixtures. Symposium on Effect of Water on Bituminous Paving Mixtures, Boston, Mass., 1958, pp. 17–34.

Bahia

H. U.

, and Ahmad

Evaluation and Correlation of Lab and Field Tensile Strength Ratio (TSR) Procedures and Values in Assessing the Stripping Potential of Asphalt Mixes. WisDOT Highway Research Study SPR#0092-45-91. Wisconsin Department of Transportation, Madison, 1999.

Kanitpong

, and Bahia

H. U.

Evaluation of HMA Moisture Damage in Wisconsin As It Relates to Pavement Performance. International Journal of Pavement Engineering, Vol. 9, No. 1, 2008, pp. 9–17.

Caro

, and Alvarez

Evaluación de la Susceptibilidad al Daño por Humedad de Mezclas Asfálticas Empleando Propiedades Termodinámicas. Revista Facultad de Ingenieria Universidad de Antioquia, No. 58, 2011, pp. 95–104.

Moraes

, Velasquez

, and Bahia

H. U.

Measuring the Effect of Moisture on Asphalt–Aggregate Bond with the Bitumen Bond Strength Test. In Transportation Research Record: Journal of the Transportation Research Board, No. 2209, Transportation Research Board of the National Academies, Washington, D.C., 2011, pp. 70–81.

Moisture Sensitivity of Asphalt Pavements National Seminar, Transportation Research Board, San Diego, Calif., 2003.

Moraes

Validation of the Bitumen Bond Strength Test Using Surface Energy Measurements. MS thesis. University of Wisconsin–Madison, 2011.