Abstract
The effects of adding micro-carbon fibers on the electro-mechanical response of macro-steel fiber-reinforced concretes (MSFRCs) under tension were investigated. Two MSFRCs were investigated and they had identical mortar matrix but different fiber contents: MSFRC1 and MSFRC2 contained 1.0 and 1.5 vol.% fibers, respectively. The volume contents of added micro-carbon fibers were 0 to 1.5 vol.% in MSFRC1 and 0 to 0.75 vol.% in MSFRC2, respectively. The addition of 0.5 vol.% micro-carbon fibers, in both MSFRC1 and MSFRC2, produced significantly enhanced damage-sensing capability and still retained their strain-hardening performance together with multiple micro cracks. However, when the content of carbon fibers was more than 0.5 vol.%, the MSFRCs generated tensile strain-softening behavior and reduced damage-sensing capability. Furthermore, the effects of temperature and humidity on the electrical resistivity of MSFRCs were investigated, as were the effects of adding multi-walled carbon nanotubes on the damage-sensing capability of MSFRCs.
Highlights
Structural health monitoring (SHM) has been frequently applied to monitor and inspect the structural performance of buildings and civil infrastructure during their long-term service [1,2].Current SHM methods generally have utilized embedded or attached sensors; those sensors have high cost, low sensitivity and low durability [3]
The strain-hardening zone of macro-steel fiber-reinforced concretes (MSFRCs) using conductive fiber importantly causes a reduction in electrical resistivity and damage-sensing capability of material, this mechanism was reported in detail by Nguyen et al [14]
An attempt to enhance the damage-sensing capacity of MSFRCs was experimentally conducted in this study
Summary
Structural health monitoring (SHM) has been frequently applied to monitor and inspect the structural performance of buildings and civil infrastructure during their long-term service [1,2]. An effort to enhance the self damage-sensing capability of MSFRCs was conducted by adding micro-carbon fibers (CFs) or carbon nanotubes (CNTs) into them Both CFs and CNTs are well-known as conductive materials with very high aspect ratio and high tensile strength. The synergy between macro-steel fiber and carbon additives is hoped to generate a favorable effect on electro-mechanical behaviors of MSFRCs. Besides, the electrical resistivity of MSFRCs, a key property that influences their damage-sensing capability, should be investigated. The electrical resistivity of MSFRCs, a key property that influences their damage-sensing capability, should be investigated This situation has motivated the authors to perform this study, which is based on some partial previous reports [19,20,21] from the first author. The objectives of this study can be listed as follows: (1) to explore the influences of various additive types on the electrical resistivity of MSFRCs, (2) to explore the effects of humidity and temperature on electrical resistivity of MSFRCs, (3) to investigate the influences of carbon fiber volume fraction on the electro-tensile behavior of MSFRCs, (4) to review the damage-sensing capabilities of some MSFRCs, and (5) to investigate the effects of aligned multi-walled carbon nanotubes (MWCNTs) on the electro-tensile behavior of MSFRCs
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