| abstract |
A new strain/stress sensor based on the concept of reversible crack opening in a composite material. Crack opening increases the electrical resistance, which is the signal provided by the sensor. The new technology is manifested in concrete and mortar containing electrically conducting short fibers (e.g., carbon fibers and steel fibers). Carbon fibers serve to greatly decrease the crack height so that apparently reversible crack opening occurs. The crack opening is accompanied by fiber pull-out, resulting in fiber-matrix contact resistivity increase, thus allowing sensing under cyclic as well as static loading. A part of the resistance change is irreversible, so it provides memory of the first deformation. |