Editor’s Note

The subject of the Special Edition advertised in the Call for Papers was ''Performance of Concrete Structures with Unique Materials, Reinforcement or Geometry.''Papers were solicited and invited by the guest editor, and a total of 7 papers are published in this Special Edition.Indeed, all the accepted papers are well in line with this theme.Three papers are on the subject of fiber-reinforced polymers (FRP) in conjunction with concrete structures; one paper is about the development of a cold-formed steel-concrete composite system; two papers are on the behavior of concrete with recycled concrete aggregates and prestressed high-strength concrete structures; and one paper is regarding the issue of transverse deck cracking and crack sealant materials.The guest editor was keen to solicit papers on the following topics: (1) state of the art review of prior research on concrete and concrete structures with unique materials, reinforcement or geometry; (2) state of the practice on structural design, construction, rehabilitation and repair of relevant structures; (3) large-scale and smaller scale experimental research; (4) analytical and numerical research; and (5) field monitoring and observation.Ideally, this Special Edition includes all of these components.Of seven, three papers deal with emerging and novel systems/materials for new construction and four papers are intended for the repair, rehabilitation, and maintenance of existing structures.In terms of the specific methodology used, the following approach has been taken: (1) experimental techniques