Carbon-fiber-reinforced cement-based sensors

Abstract

The addition of carbon fibers has proved to be one of the most effective ways of improving the electrical conductivity of ordinary cement pastes. This implies that such materials can be used in strain, temperature, and chemical sensing. The present study was aimed at the development of such sensors. Inexpensive, petroleum-pitch-based, mesophase, high-modulus carbon fibers were used throughout. It was seen that materials with high conductivity could be obtained by reinforcing hydrated cement paste with carbon fibers. Electronic conduction was seen as the dominant mode over electrolytic conduction. Compared with strain, the influence of temperature on the electrical resistivity was found to be insignificant, implying a lack of need for temperature correction. Results also indicate that these sensors can be excellent crack detectors.Key words: carbon-fiber-reinforced cement-based composites, structural health monitoring, sensor, electrical resistivity, compressive strain, temperature, moisture content, chloride concentration, fiber volume fraction, water/cementitious ratio, cracking.

Influence of micro-cracking on the composite resistivity of Engineered Cementitious Composites

“…The use of piezoresistivity of concrete containing carbon and steel fibers and other conductive fillers to detect linear-elastic strain and onset of cracking has recently gained interest among researchers. Significant advances in this field are credited to Chung [12,14,[31][32][33], Beaudoin [34], Banthia [35,36], Han [37], Azhari [38], and their co-workers. However, none of these studies investigated the influence of inelastic multiple micro-cracking of a strain hardening cementitious composite under direct tensile loading on the composite resistivity, which is needed for developing self-sensing, damage tolerant structural materials.…”

Experimental Investigation of Self-Sensing Carbon Fiber Reinforced Cementitious Composite for Strain Measurement of an RC Portal Frame

“…However, the factors that affect the conductivity properties of CFRCs include carbon fiber length and content [9], the test specimen's age and moisture content [10], and the resistance measurement method [9]. In order to reduce variations due to experiments, this research used a fixed diameter of 7 m, length of 15 mm, and content of 0.2 vol.% for the carbon fibers.…”

Applications of Self-Sensing Concrete

“…Chacko studied electrical resistivity versus the load behavior of carbon fiber cement paste sensors embedded in concrete cylinders and beams under compressive and flexural loading [24]. The sensors might more accurately monitor strain in the concrete members in their electrical resistivity reading if they were made of resilient material with high yield strength and low modulus of elasticity.…”