Self-Monitoring of Damage Evolution in Asphalt Concrete Based on Electrical Resistance Change Method

Abstract

Asphalt pavements expose early damage during their service life. The early damage grows internally until it accumulates and transforms into macro-damage that leads to structural failure. To promote real-time monitoring of internal damage evolution in asphalt pavements, this study proposes an electrical resistance change (ERC) method that exploits the piezoresistive properties of conductive asphalt concrete as a nondestructive testing technique capable of detecting microstructural defects. For this purpose, the traditional asphalt mixtures were first made electrically conductive by adding carbon fibers and iron tailing aggregates as conductive aggregates to satisfy the piezoresistivity requirements. Secondly, piezoresistivity experiments were performed by applying cyclic tensile force in fatigue and progressively increasing mode. The self-monitoring ability of damage evolution was assessed based on the correlation between the fractional change in electrical resistance (FCR), displacement, and damage degree for each mode of the force application. It was observed that under fatigue mode, the FCR and displacement increase upon loading and decrease reversibly upon unloading in each cycle. Compared with the displacement, the FCR exhibits partial reversibility upon unloading, indicating damage initiation in each cycle. The damage grows with the number of loading cycles until it accumulates in the elastic regime and gradually affects the load-carrying capacity of the mixture. Under a progressively increasing mode, the mixture exhibits a good correlation between the FCR and force in the elastic regime, ensuring real-time monitoring of internal micro-damage. However, the FCR develops a nonlinear correlation with the force in the inelastic regime that reflects damage to the conductive network and eventually structural failure. In summary, the ERC method provides real-time monitoring of microstructural defects that manifest as early damage and gradually transform into macro-damage under repeated traffic loads.

A review of conductive additives for enhancing the electrical properties of self-sensing asphalt

“…Besides, some studies show opposite results, as the mechanical performance has been observed to decline in some studies if both fibers and fillers are used in combination [18]. The combined usage of graphite and carbon fiber is reported to have negative effect on the mechanical properties of asphalt when graphite is used in larger content (i.e., more than 20%) [23].…”

“…The cost of additive material for improving the conductivity of mixture is also an important factor to be kept in mind while deciding to use a specific type [6,35]. Though several conductive additives being used by researchers for imparting conductivity in modified asphalt, a clear and holistic understanding of the additives used individually or in combination still needs to be developed and considered as a challenge for more efficient future use of conductive modified asphalt [23]. Nevertheless, selection of conductive additives is strongly based on the condition not to affect the durability and performance of asphalt concrete made with such additives [7].…”