Smart Cementitious Sensors with Nano-, Micro-, and Hybrid-Modified Reinforcement: Mechanical and Electrical Properties

Abstract

The current paper presents the results of an experimental study of carbon nano-, micro-, and hybrid-modified cementitious mortar to evaluate mechanical performance, energy absorption, electrical conductivity, and piezoresistive sensibility. Three amounts of single-walled carbon nanotubes (SWCNTs), namely 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, and 0.3 wt.% of the cement mass, were used to prepare nano-modified cement-based specimens. In the microscale modification, 0.05 wt.%, 0.5 wt.%, 1.0 wt.% carbon fibers (CFs) were incorporated in the matrix. The hybrid-modified cementitious specimens were enhanced by adding optimized amounts of CFs and SWCNTs. The smartness of modified mortars, indicated by their piezoresistive behavior, was investigated by measuring the changes in electrical resistivity. The effective parameters that enhance the composites’ mechanical and electrical performance are the different concentrations of reinforcement and the synergistic effect between the types of reinforcement used in the hybrid structure. Results reveal that all the strengthening types improved flexural strength, toughness, and electrical conductivity by about an order of magnitude compared to the reference specimens. Specifically, the hybrid-modified mortars presented a marginal reduction of 1.5% in compressive strength and an increase in flexural strength of 21%. The hybrid-modified mortar absorbed the most energy, 1509%, 921%, and 544% more than the reference mortar, nano-modified mortar, and micro-modified mortar, respectively. The change rate of impedance, capacitance, and resistivity in piezoresistive 28-day hybrid mortars improved the tree ratios by 289%, 324%, and 576%, respectively, for nano-modified mortars and by 64%, 93%, and 234%, respectively, for micro-modified mortars.

Performance, Mechanical Properties and Durability of a New Type of UHPC—Basalt Fiber Reinforced Reactive Powder Concrete: A Review

“…Thanks to the continuous deepening of research, fiber-reinforced concrete materials have come into being. A large number of tests demonstrate that fiber incorporation not only fully realizes the goal of improving the cracking resistance of concrete, but also has a positive effect on the concrete’s mechanical properties, electrical properties, and durability [ 9 , 10 , 11 ]. However, it is worth noting that different types of fiber admixtures have varying effects on the performance improvement of UHPC materials.…”

Properties and durability of self‐compacting concrete incorporated with nanosilica, fly ash, and limestone powder

“…Many studies on nanofibers, such as carbon nanofibers, have found that these fibers play an important role at the nanoscale level in the cement matrix. 20,21 Nanofibers have been used to improve the mechanical properties, mainly to enhance toughness and ductility, and to reduce cracking at the nanoscale level of cementitious materials. 22,23 The number of studies on using nanoparticles to enhance concrete properties is increasing.…”

“…Nanomaterials, which include many varieties in the form of very fine powder or liquid materials, as well as nanofibers, can be used. Many studies on nanofibers, such as carbon nanofibers, have found that these fibers play an important role at the nanoscale level in the cement matrix 20,21 . Nanofibers have been used to improve the mechanical properties, mainly to enhance toughness and ductility, and to reduce cracking at the nanoscale level of cementitious materials 22,23 .…”

Mechanical Characterization of Nano-Reinforced Mortar: X-ray Micro-CT for 3D Imaging of Microstructure

“…The mechanical capacities of cementitious composites, such as flexural strength, compressive strength, and toughness, or thermoelectrical properties such as conductivity, are powerfully affected by the additives' dispersion and the pore structure of the material [5,6]. In the pore characterization process, with micro-CT and pore size distribution, the diameter of pores plays a significant role [7] Although conventional volume-based theory considers the perfect spherical morphology according to the maximal ball algorithm, usually characterized by the pore size distribution of the material, these methods provide limitations in relating the anisotropic or heterogeneous pore properties.…”