Multifunctional components from carbon concrete composite C³ – integrated, textile-based sensor solutions for in situ structural monitoring of adaptive building envelopes

Abstract

This contribution will introduce carbon-reinforced concrete components (so-called carbon concrete composites, or C3) with sensor functionalities for innovative building envelopes. For a continuous in situ structural monitoring, these textile-reinforced concrete components are equipped with textile sensor networks consisting of resistive carbon fiber sensors (CFSs), which are integrated into the carbon fiber non-crimp fabrics of the concrete reinforcement by multiaxial warp-knitting. The in situ CFSs, consisting of 1 k or 50 k carbon fiber roving with added staple fiber/multifilament dielectric cladding, are later integral to the load-distributing elements of the concrete component, and elongations within these are easy to record with good correlation to ohmic resistance changes. Gage factors of k = 0.52–1.23 at linearity deviations of ALin = 4.0–8.7% are feasible. This allows a monitoring of C3 building envelopes for structural mechanical changes caused by physical changes within the component through mechanical or thermal loads or deformation and cracks.

Strain sensing characteristics using piezoresistivity of semi-conductive silicon carbide fibers

“…Therefore, the semi-conductive SiC fibers showed high strain sensitivity with an average GF of 8.25. This GF was very high when compared to electrical resistance strain gauges with GFs of about 2, carbon fibers with GFs of about 2 [15][16][17][18][19][20][21][22][23][24] and CNT coated fibers with GFs of 1.6-2.3 [14] The repeatability on the resistance change measurement for the SiC fibers was evaluated by calculating the coefficient of variation (CV) of the fractional resistance changes at maximum load using equation (4). The results were listed in table 4.…”

“…Therefore, utilization of piezoresistivity of the conductive fibers itself can provide an alternative method for measuring the strain of insulating composite materials. As carbon fibers are representative piezoresistive fibers, previous studies have investigated the piezoresistive characteristics of carbon fibers not only for a single carbon fiber [15] but also for carbon fiber bundles such as yarns [16][17][18][19][20][21][22] and rovings [23,24]. It was reported that carbon fibers had the gauge factor (GF) of about 2 and showed excellent linearity in resistance change [16][17][18][19][20][21][22][23][24].…”

“…As carbon fibers are representative piezoresistive fibers, previous studies have investigated the piezoresistive characteristics of carbon fibers not only for a single carbon fiber [15] but also for carbon fiber bundles such as yarns [16][17][18][19][20][21][22] and rovings [23,24]. It was reported that carbon fibers had the gauge factor (GF) of about 2 and showed excellent linearity in resistance change [16][17][18][19][20][21][22][23][24]. In subsequent studies, the strain sensing performance of carbon fibers were enhanced by applying an appropriate error compensation method [20] and improving the alignment of carbon fibers [20,21].…”

“…In subsequent studies, the strain sensing performance of carbon fibers were enhanced by applying an appropriate error compensation method [20] and improving the alignment of carbon fibers [20,21]. Moreover, the piezoresistivity of embedded carbon fibers was investigated by embedding carbon fibers into a polymeric matrix [16][17][18][19][20][21]23] or cement matrix [22][23][24].…”