Biaxial compression in carbon-fiber-reinforced mortar, sensed by electrical resistance measurement

The stress-sensing behavior of carbon-fiber-reinforced mortar under biaxial compression was found to be different with that under uniaxial compression. For both the case of uniaxial compression and the case of biaxial compression, with an increase in the compressive stress, the fractional change in resistance in any direction decreases gradually at first, and then increases with increasing stress. But the stress level at which the fractional change in resistance starts to increase, referred to as the critical stress in this paper, varies with the loading style and the direction in which the resistance is measured. The critical stress related to the biaxial compression and the stress direction is larger than that related to the uniaxial compression and the stress direction. But on the other hand, the critical stress related to the biaxial compression and the direction other than the two stress directions is less than that related to the uniaxial compression and the direction other than the stress direction. The piezoresistivity of carbon-fiber-reinforced mortar under biaxial compression is more sensitive than that under uniaxial compression. (c) 2004 Elsevier Ltd. All rights reserved.