Electrically conductive asphalt concrete: Towards a theory of practice

Ice and snow on paved surfaces have always been considered a source of concern for transportation agencies and users. On airfield pavements, slippery surfaces double concerns in terms of flight delays or cancellation. Currently, while mechanical approaches like snow plowing and using deicing chemicals are widely used to facilitate more favorable conditions for transportation agencies and users, neither mechanical approaches nor deicing materials can provide sufficiently acceptable ice and snow surfaces during harsh wintertime. Fortunately, techniques using resistive heating of pavement material can be used to free pavement surfaces from ice and snow using a heated pavement system fabricated with electrically-conductive asphalt concrete (ECAC) with embedded electrodes connected to an electrical power source. This study set out to fabricate an ECAC mixture with high electrical conductivity able to melt ice and snow. Given this goal, asphalt mixture was dosed with conductive additive-carbon fiber (CF)- using a promising mix design to provide a homogeneous composite material. The electrical characteristics of such a mixture was investigated both through volume resistivity measurements and active infrared thermography (IRT). To provide scientific insight, the mechanisms of creating heating and the resulting patterns are discussed in terms of electrical theory applied to an HPS system fabricated from ECAC material. In addition to the determining functional performance of ECAC material, its mechanical performance was evaluated to ensure that such a specific mixture can deal with stress and strain applied through environmental and mechanical loading. The results of this study revealed that the fabricated ECAC material could successfully provide enough thermal energy to melt ice and snow at very low temperatures, and also showed that the fabricated mixture had better mechanical performance than a conventional asphalt mixture

Determining Asphalt Mixture Properties Using Imaging Techniques

This study introduces imaging technology to determine the bulk specific gravity (Gmb) of compacted asphalt mixture specimens. Using an advanced three-dimensional scanner, a fast, accurate technique for determining compacted asphalt mixture specimen Gmb was developed. The feasibility of this technique was evaluated by testing a collection of asphalt mixtures, including dense-graded and stone mastic asphalt mixtures. The results were compared with those obtained using the currently-specified Gmb measurement methods of AASHTO T166 and CoreLok. The proposed scanning technique was also used for both laboratory-prepared and field-cored specimens to determine its reliability and reproducibility. The study results suggest the proposed imaging technique is effective in decreasing Gmb measurement variation as well as in improving the accuracy and reproducibility. Additionally, the results indicate the proposed technique can be applied to any asphalt specimen, regardless of mixture type, aggregate sizes, or fabrication technique

Environmentally Tuning Asphalt Pavements Using Phase Change Materials

Environmental conditions are considered an important factor influencing asphalt pavement performance. The addition of modifiers, both to the asphalt binder and the asphalt mixture, has attracted considerable attention in potentially alleviating environmentally induced pavement performance issues. Although many solutions have been developed, and some deployed, many asphalt pavements continue to prematurely fail due to environmental loading. The research reported herein investigates the synthetization and characterization of biobased Phase Change Materials (PCMs) and inclusion of Microencapsulated PCM (μPCM) in asphalt binders and mixtures to help reduce environmental damage to asphalt pavements. In general, PCM substances are formulated to absorb and release thermal energy as the material liquify and solidify, depending on pavement temperature. As a result, PCMs can provide asphalt pavements with thermal energy storage capacities to reduce the impacts of drastic ambient temperature scenarios and minimize the appearance of critical temperatures within the pavement structure. By modifying asphalt pavement materials with PCMs, it may be possible to tune the pavement to the environment

Electrically conductive asphalt concrete: An alternative for automating the winter maintenance operations of transportation infrastructure

Hot mix asphalt (HMA) was modified with carbon fiber (CF) to achieve electrically conductive asphalt concrete with applications to pavement anti-icing and de-icing. The volume resistivity of such electrically conductive asphalt concrete was compared with that of electrically conductive asphalt mastic. Then, the temperature increase, the power consumption, and the snow melting capability of electrically conductive asphalt concrete were evaluated. Lastly, a conceptual cost estimation was performed based on data obtained from lab investigations, publicly available bid records, and the experience gained from the field implementation of a heated pavement system made of electrically conductive portland cement concrete

Determining Asphalt Mixture Properties Using Imaging Techniques

SPR-4415This study introduces imaging technology to determine the bulk specific gravity (Gmb) of compacted asphalt mixture specimens. Using an advanced three-dimensional scanner, a fast, accurate technique for determining compacted asphalt mixture specimen Gmb was developed. The feasibility of this technique was evaluated by testing a collection of asphalt mixtures, including dense-graded and stone mastic asphalt mixtures. The results were compared with those obtained using the currently-specified Gmb measurement methods of AASHTO T166 and CoreLok. The proposed scanning technique was also used for both laboratory-prepared and field-cored specimens to determine its reliability and reproducibility. The study results suggest the proposed imaging technique is effective in decreasing Gmb measurement variation as well as in improving the accuracy and reproducibility. Additionally, the results indicate the proposed technique can be applied to any asphalt specimen, regardless of mixture type, aggregate sizes, or fabrication technique

Electrically conductive asphalt concrete: Towards a theory of practice

Ice and snow on paved surfaces have always been considered a source of concern for transportation agencies and users. On airfield pavements, slippery surfaces double concerns in terms of flight delays or cancellation. Currently, while mechanical approaches like snow plowing and using deicing chemicals are widely used to facilitate more favorable conditions for transportation agencies and users, neither mechanical approaches nor deicing materials can provide sufficiently acceptable ice and snow surfaces during harsh wintertime. Fortunately, techniques using resistive heating of pavement material can be used to free pavement surfaces from ice and snow using a heated pavement system fabricated with electrically-conductive asphalt concrete (ECAC) with embedded electrodes connected to an electrical power source. This study set out to fabricate an ECAC mixture with high electrical conductivity able to melt ice and snow. Given this goal, asphalt mixture was dosed with conductive additive-carbon fiber (CF)- using a promising mix design to provide a homogeneous composite material. The electrical characteristics of such a mixture was investigated both through volume resistivity measurements and active infrared thermography (IRT). To provide scientific insight, the mechanisms of creating heating and the resulting patterns are discussed in terms of electrical theory applied to an HPS system fabricated from ECAC material. In addition to the determining functional performance of ECAC material, its mechanical performance was evaluated to ensure that such a specific mixture can deal with stress and strain applied through environmental and mechanical loading. The results of this study revealed that the fabricated ECAC material could successfully provide enough thermal energy to melt ice and snow at very low temperatures, and also showed that the fabricated mixture had better mechanical performance than a conventional asphalt mixture.</p

Electrically conductive asphalt concrete: An alternative for automating the winter maintenance operations of transportation infrastructure

Hot mix asphalt (HMA) was modified with carbon fiber (CF) to achieve electrically conductive asphalt concrete with applications to pavement anti-icing and de-icing. The volume resistivity of such electrically conductive asphalt concrete was compared with that of electrically conductive asphalt mastic. Then, the temperature increase, the power consumption, and the snow melting capability of electrically conductive asphalt concrete were evaluated. Lastly, a conceptual cost estimation was performed based on data obtained from lab investigations, publicly available bid records, and the experience gained from the field implementation of a heated pavement system made of electrically conductive portland cement concrete.This is a manuscript of an article published as Arabzadeh, Ali, Mohammad Ali Notani, Ayoub Kazemian Zadeh, Ali Nahvi, Alireza Sassani, and Halil Ceylan. "Electrically conductive asphalt concrete: An alternative for automating the winter maintenance operations of transportation infrastructure." Composites Part B: Engineering (2019): 106985. DOI: 10.1016/j.compositesb.2019.106985. Posted with permission.</p