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CN-121974631-A - Novel nano synergistic high-strength self-sensing cement-based material

CN121974631ACN 121974631 ACN121974631 ACN 121974631ACN-121974631-A

Abstract

The invention discloses a novel nano synergistic high-strength self-sensing cement-based material, which is formed by the cooperation of cement-based cementing material, aggregate, water, a water reducing agent, a multi-wall carbon nano tube, nano titanium dioxide, nano montmorillonite and the like according to a specific proportion. The multi-wall carbon nano tube can form a high-sensitivity three-dimensional conductive network in a cement matrix after surface modification and pre-dispersion treatment, nano titanium dioxide is filled in pores of cement hydration products, the compactness and durability of the material are obviously enhanced, the conductivity is enhanced, nano montmorillonite is dispersed in the matrix in a lamellar structure, and microcrack expansion is inhibited and the overall toughness is improved through a bridging effect.

Inventors

  • LIU YAO
  • GAO CHAO
  • PENG CHENG
  • TONG JIAYU
  • HE JIAMING
  • ZHANG GUANYI
  • LIU HUIZHAO
  • YANG BOWEN

Assignees

  • 东北林业大学

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. The novel nano synergistic high-strength self-sensing cement-based material is characterized by comprising a cement-based cementing material, aggregate, water, a water reducing agent and functional nano components, wherein the functional nano components comprise multi-wall carbon nano tubes, nano titanium dioxide and nano montmorillonite.
  2. 2. The high-strength self-sensing cement-based material according to claim 1, wherein the multi-wall carbon nanotubes are doped in an amount of 0.05 to 0.3% of the total mass of the cement, the nano titanium dioxide is doped in an amount of 0.5 to 3.0% of the total mass of the cement, and the nano montmorillonite is doped in an amount of 0.5 to 2.5% of the total mass of the cement.
  3. 3. The high strength self-sensing cementitious material of claim 1 or 2, wherein the multiwall carbon nanotubes are modified by surface carboxylation or hydroxylation and are incorporated after being treated by a pre-dispersion process to form a uniform suspension slurry.
  4. 4. The high strength self-sensing cementitious material of claim 1 or 2, wherein the nano titania is anatase having an average particle size between 20-50 nm.
  5. 5. The high strength self-sensing cementitious material of claim 1 or 2, wherein the nano montmorillonite is a calcium-based nano montmorillonite, is in the form of a white powder, and has not been subjected to additional processing prior to use.
  6. 6. A method for preparing a high-strength self-sensing cement-based material according to any one of claims 1 to 5, comprising the steps of mixing the pre-dispersed multiwall carbon nanotube slurry, the nano montmorillonite suspension, the nano titanium dioxide, part of the mixing water and the water reducing agent to form uniform functional slurry, and stirring the functional slurry, cement, aggregate and other dry components together until the functional slurry, the aggregate and the water reducing agent are uniformly mixed.
  7. 7. The method according to claim 6, wherein the pre-dispersing treatment of the multi-walled carbon nanotubes comprises the steps of forming a stable dispersed suspension slurry of the surface-modified multi-walled carbon nanotubes in an aqueous solution containing a dispersing agent by ultrasonic and high-speed shearing treatment.
  8. 8. A method of structural health monitoring, characterized in that a civil engineering structural member to be monitored is constructed or repaired using the high-strength self-sensing cement-based material as claimed in any one of claims 1 to 5, and the stress, strain state and damage evolution inside the member are sensed in real time by monitoring the resistance or resistivity change of the member during service.
  9. 9. The method of claim 8, wherein the step of evaluating and pre-warning the health status of the structure by analyzing the time domain and amplitude characteristics of the resistance or resistivity variation signal, wherein the health status includes an elastic working phase, a plastic development phase, a microcrack initiation phase and a macroscopic crack propagation phase.
  10. 10. The method of claim 8 or 9, wherein the civil engineering structural member comprises a critical stress site of a bridge, tunnel, building, dam, or piping lane.

Description

Novel nano synergistic high-strength self-sensing cement-based material Technical Field The invention belongs to the field of novel multifunctional materials, and mainly relates to a novel nano synergistic high-strength self-sensing cement-based material. Background Traditional cement-based materials, which are the core of modern infrastructure, have long relied on periodic visual inspection and local non-destructive inspection techniques for structural safety assessment. The traditional methods consume a large amount of manpower and material resources, are difficult to capture the initiation and continuous evolution process of early micro-damage inside the structure due to the discreteness and hysteresis, and cannot meet the urgent requirements of modern large-scale engineering on real-time, online and intelligent structural health monitoring and early warning systems. In order to break through this limitation, the inherent "perceptive" capabilities of concrete materials are given so that they can convert the internal stress, strain and damage states into measurable physical signals, which is an important research direction in the field of civil engineering materials for the last twenty years. In early research, researchers have primarily sought to impart conductivity and self-sensing functions to cement-based composites by incorporating macroscopic conductive phases, such as steel fibers, carbon fibers, and the like. Although the method realizes the effect of the resistance changing along with the stress to a certain extent, the inherent technical defects limit the practical application. To form a continuous conductive path, the fiber loading is typically high, which often results in a significant decrease in workability of the fresh concrete and may adversely affect the critical mechanical properties such as compressive strength, elastic modulus, etc. of the hardened concrete. The macroscopic fiber mainly forms a conductive network through physical lap joint, has low response sensitivity to micro-strain and early microcracks, large electrical signal noise and poor repeatability, is easy to corrode in the service process of aggressive environments such as long-term humidity, salt fog and the like, is easy to degrade at the interface between the carbon fiber and a matrix, leads to the stability of the conductive network to be reduced, and is difficult to ensure the reliable monitoring of the whole life cycle due to serious drift of sensing signals. In order to alleviate the limitations of macroscopic conductive phases, carbon-based nanomaterials represented by carbon nanotubes and graphene have been attracting attention due to their unique electrical and mechanical properties. A large number of researches at home and abroad show that the carbon nano tube can form a high-efficiency seepage conductive network in a cement matrix under the condition of low doping amount, has extremely high sensitivity to tiny strain and damage, and has broad theoretical prospect. However, carbon nanotubes have a large specific surface area and extremely high surface energy, and are susceptible to agglomeration in a strongly alkaline cement slurry environment. At the moment, the dispersibility can be improved to a certain extent by means of surface acidification, silane coupling agent modification and the like, but under the coupling action of complex dynamic hydration process and long-term various service environments, how to maintain the structural integrity and functional stability of the nano conductive network is still a core technical obstacle for the trend of the nano conductive network to engineering practice. In order to break the bottleneck of single nanomaterial application, a strategy of multicomponent nanocomposite modification has been developed. The nano titanium dioxide and the carbon nano tube are mixed, and the durability of the material is expected to be improved by virtue of the micro filling effect of the titanium dioxide while the conductivity is improved. At present, research is carried out on simple physical mixing of binary systems, and systematic design and regulation of deep synergistic mechanisms among multiple nano components are lacked. The nano titanium dioxide can optimize a part of pore structure, but has limited effect of improving the dispersibility of the carbon nano tube, and has insufficient contribution to the improvement of the toughness and the cracking resistance of the material. Under the stress-environment coupling effect of the complex actual engineering, the self-sensing function of the sensor often shows the problems of signal attenuation, baseline drift, weak anti-interference capability and the like, and the engineering application with high reliability and long service life has obvious difference. The invention discloses a novel nano synergistic high-strength self-sensing cement-based material, which is formed by the cooperation of cement-based cementing material, aggregate, wat