What is it about?

Based on the specific characteristics of bituminous materials, and the need on knowing its thermal properties concerning the understanding and the improvement of the behavior facing the temperature changing, this invention is a suitable method for the estimation of thermal conductivity of asphaltic binders solving issues like cost, and accuracy. Additionally, this method could be implement flexibly following the calibration step described in the base document.

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Why is it important?

In the Civil Engineering field, asphalt concrete represents the third most widely used resource in the world, being asphalt-paved roads its principal usage. One of the most important components of asphalt concrete is bitumen. Bitumen is a highly susceptible viscoelastic material to temperature changes. This can be brittle as glass at low temperature and flow like oil at high temperatures (DeDene, et al., 2016). Then, the determination of the thermal conductivity of bitumen becomes very important to understand and improve its thermal performance. Analytical models in different studies have been used to calculate the thermal conductivity, however, the accuracy of each model and technique is narrowed by the physical properties and other factors of each material to test. Therefore, quantity and modeling of thermal conductivity are complex and demand high precision. The approaches and the models used to study thermal behavior of materials have to be clearly defined (Yüksel, 2016). Based on the specific characteristics of bituminous materials, and the need on knowing its thermal properties concerning the understanding and the improvement of the behavior facing the temperature changing, and even to address the urban heat island, this invention represents an alternative method for the estimation of thermal conductivity of asphaltic binders solving issues like cost, and accuracy.

Perspectives

The exactitude of different methods for calculating thermal conductivity is extensively debated in several fields, in addition, the wide range of thermal characteristics of different materials makes to have a lot of methods for the estimation of thermal conductivity (Yüksel, 2010). Along the last two decades, the accuracy and the understanding of the principles of heat transfer have been improved for several materials. These techniques present different ranges of thermal conductivity even for a same material, different accuracy, temperature ranges, and specimen type. (Yüksel, 2016). There are very few test methods and equipment to measure thermal conductivity of asphalt binders. Some of those are expensive and require special equipment and instrumentation. The authors of this invention developed and validated a new testing technique to measure thermal conductivity of asphalt binders with suitability and accuracy.

Carlos Javier Obando Gamboa
Arizona State University

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This page is a summary of: Estimating the Thermal Conductivity of Asphalt Binders, Journal of Testing and Evaluation, October 2021, ASTM International, DOI: 10.1520/jte20210208.
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