Smart materials for heated concrete pavement systems
Today’s predominant pavement de-icing methods rely on mechanical removal and chemical de-icers. The limitations of such approaches include high investment in time/labor, pavement damage, and traffic interruption, and they have given rise to a need for novel alternatives to replace or complement existing traditional methods. This study, inspired by such a need, has approached the problem of pavement deicing from a heated pavement systems (HPS) prospective. The study has sought to investigate the feasibility of using smart materials in electrically heated pavement systems (EHPS). To this end, two types of composite materials: (1) portland cement-based electrically conductive concrete (ECON), and (2) polymer-based electrically conductive coatings (ECOT) were studied.
ECON mix design, using carbon fibers (CF) of micrometer-scale diameter and millimeter-scale length as an electrically conductive additive, was prepared and optimized for pavement applications in accordance with relevant standards and specifications. The optimum carbon fiber dosage rate for achieving desirable electrical conductivity and avoiding excessive fiber use was determined based on fiber percolation phenomenon. The ECON HPS system design and configuration were evaluated by finite element (FE) analysis and laboratory tests, and the feasibility of using ECON was then investigated both at laboratory scale and through a real-size EHPS test section at the Des Moines International Airport. The performance of the ECON HPS was evaluated in terms of energy demand for snow-melting, energy conversion efficiency, and service life.
An electrically conductive composite coating, made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler, was produced and applied as an electrically heated layer on the surface of portland cement concrete (PCC). The CMF dosage rate required to achieve desirable volume conductivity, heating capability, and durability was investigated. Coating durability was evaluated using a loaded cyclic wheel path to simulate coating performance on pavement surfaces. This research has introduced PU-CMF coating as a versatile smart material with application to various fields such as EHPS and self-sensing structures.