Edge Zone Effect in Measurements of Asphalt Mixture Thermal Properties Using Transient Method

Area of Science:

• Civil Engineering
• Materials Science
• Geotechnical Engineering

Background:

• Thermal conductivity and specific heat capacity are crucial for road pavement heat transfer.
• Transient methods for thermal property testing lack standardized procedures for asphalt.
• Heterogeneous asphalt mixtures present challenges for accurate thermal property determination.

Purpose of the Study:

• To systematically quantify the edge zone effect in asphalt mixtures.
• To assess the influence of edge effects on thermal conductivity and diffusivity.
• To identify methodological consequences and limitations of transient methods for asphalt.

Main Methods:

• Utilized the Modified Transient Plane Source (MTPS) method for laboratory testing.
• Investigated slab-shaped specimens of a heterogeneous asphalt mixture.
• Focused on quantitative determination and practical identification of the edge zone width.

Main Results:

• A distinct edge zone effect was observed in thermal property measurements.
• Thermal conductivity and diffusivity showed variations up to 17% and 18% near specimen edges, respectively.
• The study identified significant methodological risks and limitations due to the edge effect.

Conclusions:

• The edge zone effect necessitates methodological guidelines for testing asphalt mixtures.
• Standardized procedures are crucial for reliable transient thermal property measurements in road materials.
• Findings support the development of dedicated standards for asphalt testing.