Piezoresistive response of conductive Hot Mix Asphalt mixtures modified with carbon nanofibers

• Dispersing carbon nanofibers in HMA mixtures makes it a smart material with piezoresistive effect.
• Wire embedded electrode provide better results in comparison to plate electrodes.
• Modified HMA mixtures exhibited significant piezoresistivity response at various loading types and temperatures.

In recent years, “smart structures” experienced significant popularity in civil engineering. Such structures, referred to as intelligent structures, are built with combination of smart and conventional materials and have intelligent systems that cannot only gather information and perform tasks, but also sense variation in conditions of the materials and adapt accordingly. Conductive Hot Mix Asphalt (HMA) mixtures are constructed by modifying with electrically conductive materials. Conductive HMA mixtures would potentially make many technologies applicable to pavements including, but not limited to; thermal electric de-icing of airport runways or highways, cathodic protection of concrete bridge decks, pavement damage sensing, truck weigh-in-motion, and so forth. Dispersing carbon nanofibers (CNF) in HMA mixtures makes it a smart material as it develops a piezoresistive effect. The main objective of the study is to develop a smart HMA mixture by using electrically conductive material such as carbon nanofibers (CNF). The CNF modified HMA mixtures would have the ability to respond to loading. An exploratory investigation for piezoresistive response of CNF modified HMA mixtures under various types of loading, frequencies, and temperatures were evaluated. Stress–strain response due to applied load and its relationship with the change in resistivity was discussed. It was found that out of two type of CNF used in the study one provide better piezoresistive response of HMA. It was determined that embedment of copper wire electrodes is the most effective method to achieve smooth and consistent electrical response. Furthermore, polymer modified binders showed promising piezoresistive effect for medium to high temperature range.