Embedded piezoresistive cement-based stress/strain sensor

In order to develop one type of embedded piezoresistive cement-based stress/strain sensor (PCSS) to monitor the local compressive stress/strain of concrete structures, we explore the piezoresistivity of cement-based material with carbon fiber and carbon black under single compressive loading and repeated compressive loads at different loading amplitudes, and find it is reversible and stable within the elastic regime. This justifies the use of cement-based material with carbon fiber and carbon black in the manufacture of embedded PCSS. PCSS based on the piezoresistivity of cement-based material with carbon fiber and carbon black is tested with compressive stress/strain in the range 0 MPa (0 mu epsilon) to 8 MPa (476 mu epsilon) for performance evaluation. Results indicate that PCSS can be used to achieve a sensitivity of 1. 35 % MPa-1 (0.0227% mu epsilon(-1), gage factor of 227), linearity of 4.17% (4.16%), repeatability of 4.05% (4.06%) and hysteresis of 3.61% (3.62%), and the relationship between its input (compressive stress/strain) and output (fractional change in electrical resistivity) is Delta rho = - 1.35 sigma (Delta rho = -0.0227 epsilon). These findings suggest that this newly developed sensor can be used as one of the alternatives to monitor the compressive stress/strain of concrete structures. (C) 2007 Elsevier B.V. All rights reserved.