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Nanomaterials
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Concrete under Nanoscope
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Concrete under Nanoscope

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanofabrication and Nanomanufacturing".

Deadline for manuscript submissions: closed (31 July 2021) | Viewed by 18941

Special Issue Editors

Prof. Dr. Konstantin Sobolev

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Guest Editor
Department of Civil and Environmental Engineering, College of Engineering and Applied Science, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
Interests: high-performance cement; chemical admixtures and concrete; the application of bottom–up engineering in nano-admixtures and nanotechnology for cement and concrete; particle packing models; application of evolutionary algorithms; design, modeling, and application of high-strength and high-performance materials; materials with photocatalytic properties; super-hydrophobic materials; 3D printing of concrete, auxetic, and smart stress-sensing materials
Prof. Dr. Florence Sanchez

E-Mail Website
Guest Editor
Department of Civil and Environmental Engineering. Vanderbilt University, Nashville, TN, USA
Interests: multiscale performance and durability of cement-based materials; nanomodification of cement and concrete materials; 3D printing of concrete; properties and performance of nanostructures and nanomaterials; atomistic modeling at solid-solid and solid-liquid interfaces; computational materials discovery and design

Special Issue Information

Dear Colleagues,

Concrete, the most ubiquitous material, is a nano-structured, multiphase, composite material that ages over time. It is composed of an amorphous phase, nanometer to micrometer size crystals, bound water, and a wide range of porosity. The properties of concrete exist in, and the degradation mechanisms occur across multiple length scales (nano to micro to macro) where the properties of each scale derive from those of the next smaller scale. The amorphous phase, calcium–silicate–hydrate (C–S–H), is the “glue” that holds concrete together and is itself a nanomaterial. Viewed from the bottom up, at the nanoscale, concrete is a composite of molecular assemblages, surfaces (aggregates, fibers), and chemical bonds that interact through local chemical reactions, intermolecular forces, and intraphase diffusion. There is strong evidence that the processes occurring at the nanoscale ultimately affect the engineering properties and performance of the bulk material.

Nanotechnology has changed our vision, expectations, and abilities to control the material world. These developments will greatly affect modern construction and the field of cement-based materials. In spite of these developments, nanotechnology is still in its pre-exploration stage, only just emerging from fundamental research onto the industrial floor; thus, full-scale applications in concrete are still limited. Nonetheless, the tremendous potential of nanotechnology to improve the performance of concrete remains promising.

Highlights:

  • Recognize opportunities with new nano-engineered concrete;
  • Identify appropriate production methods and suitable applications for concrete with nanoparticles/nanofibers;
  • Compare the performance of nanoparticles/nanofibers in concrete;
  • Analyze the assumptions and common misconceptions related to the nanotechnology of concrete;
  • Recognize the environmental issues related to the application of nanomaterials in concrete.

Prof. Dr. Konstantin Sobolev
Prof. Dr. Florence Sanchez
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • concrete
  • nano-engineered concrete
  • concrete with nanoparticles/nanofibers
  • nanoparticles/nanofibers in concrete
  • nanotechnology of concrete
  • application of nanomaterials in concrete

Published Papers (6 papers)

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Research

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15 pages, 2598 KiB  
Article
Top-Down Production of Nano-Seeds from Activated Fly Ash Tuned for Enhancing the Early Strength in Blended Cements
by Konstantin Sobolev, Rani Pradoto, Ismael Flores-Vivian, Marina Kozhukhova and Irina Zhernovskaya
Nanomaterials 2022, 12(14), 2347; https://doi.org/10.3390/nano12142347 - 9 Jul 2022
Viewed by 1376
Abstract
To achieve the new level of blended cement performance, the slurries of Class C and F fly ash were mechano-chemically activated in a vibro-mill with superplasticizer and nanosilica. The resulting activated products were tested in mortars replacing up to 30% portland cement. The [...] Read more.
To achieve the new level of blended cement performance, the slurries of Class C and F fly ash were mechano-chemically activated in a vibro-mill with superplasticizer and nanosilica. The resulting activated products were tested in mortars replacing up to 30% portland cement. The activation process resulted in the formation of nano-seed clusters and micronized ash particles that both significantly improve the early strength of mortars as well as allow for the replacement of portland cement with industrial by-products. A small amount, 0.1% (of a binder weight), of nanosilica was used in selected compositions to improve the process of activation and facilitate the formation of nano-seeds. Due to an intensive activation of fly ash in the vibro-mill and the formation of nano-seed hydration products, the increase in the heat of the hydration flux and improvement of the mechanical properties such as compressive strength, especially in the early stages of hardening, were achieved. It is envisioned that fly ash activation and the use of supplementary cementitious materials as a precursor can induce a denser structure of cementitious matrix due to better particle packing realized with the application of the nano-seed product, nanosilica, ultra-fine particles of fly ash, and the formation of a refined C-S-H structure realized with the incorporation of the nano-seed particles. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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22 pages, 5412 KiB  
Article
Effect of Carbon Nanofiber Clustering on the Micromechanical Properties of a Cement Paste
by Lesa Brown, Catherine S. Stephens, Paul G. Allison and Florence Sanchez
Nanomaterials 2022, 12(2), 223; https://doi.org/10.3390/nano12020223 - 10 Jan 2022
Cited by 7 | Viewed by 2092
Abstract
The use of carbon nanofibers (CNFs) in cement systems has received significant interest over the last decade due to their nanoscale reinforcing potential. However, despite many reports on the formation of localized CNF clusters, their effect on the cement paste micromechanical properties and [...] Read more.
The use of carbon nanofibers (CNFs) in cement systems has received significant interest over the last decade due to their nanoscale reinforcing potential. However, despite many reports on the formation of localized CNF clusters, their effect on the cement paste micromechanical properties and relation to the mechanical response at the macroscopic scale are still not fully understood. In this study, grid nanoindentation coupled with scanning electron microscopy and energy dispersive spectroscopy was used to determine the local elastic indentation modulus and hardness of a portland cement paste containing 0.2% CNFs with sub-micro and microscale CNF clusters. The presence of low stiffness and porous assemblage of phases (modulus of 15–25 GPa) was identified in the cement paste with CNFs and was attributed primarily to the interfacial zone surrounding the CNF clusters. The CNFs favored the formation of higher modulus C–S–H phases (>30 GPa) in the bulk paste at the expense of the lower stiffness C–S–H. Nanoindentation results combined with a microscale–macroscale upscaling homogenization method further revealed an elastic modulus of the CNF clusters in the range from 18 to 21 GPa, indicating that the CNF clusters acted as compliant inclusions relative to the cement paste. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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23 pages, 5694 KiB  
Article
Achieving Ultra-High Performance Concrete by Using Packing Models in Combination with Nanoadditives
by Jesús Díaz, Jaime C. Gálvez, Marcos G. Alberti and Alejandro Enfedaque
Nanomaterials 2021, 11(6), 1414; https://doi.org/10.3390/nano11061414 - 27 May 2021
Cited by 12 | Viewed by 3107
Abstract
This paper describes the packing models that are fundamental for the design of ultra-high-performance concrete (UHPC) and their evolution. They are divided into two large groups: continuous and discrete models. The latter are those that provide the best method for achieving an adequate [...] Read more.
This paper describes the packing models that are fundamental for the design of ultra-high-performance concrete (UHPC) and their evolution. They are divided into two large groups: continuous and discrete models. The latter are those that provide the best method for achieving an adequate simulation of the packing of the particles up to nanometric size. This includes the interaction among the particles by means of loosening and wall coefficients, allowing a simulation of the virtual and real compactness of such particles. In addition, a relationship between virtual and real compactness is obtained through the compaction index, which may simulate the energy of compaction so that the particles are placed in the mold. The use of last-generation additives allows such models to be implemented with water–cement (w/c) ratios close to 0.18. However, the premise of maximum packing as a basic pillar for the production of UHPC should not be the only one. The cement hydration process affected by nanoadditives and the ensuing effectiveness of the properties in both fresh and hardened states according to the respective percentages in the mixture should also be studied. The characterization tests of the aggregates and additions (dry and wet compactness, granulometry, density and absorption) have been carried out in order to implement them numerically in the polydisperse packing model to obtain the compactness of the mixture. Establishing fixed percentages of nanoadditives in the calculation of the mixture’s compactness. The adequate ratio and proportion of these additions can lead to better results even at lower levels of compactness. The compressive strength values obtained at seven days are directly proportional to the calculated compactness. However, at the age of 28 days, better results were obtained in mixes with lower cement contents, fewer additions and lower compactness. Thus, mixes with lower cement contents and additions (silica fume and limestone filler) with a compactness of φ = 0.775 reached 80.1 MPa of strength at 7 days, which is lower than mixes with higher cement contents and number of additions (SF, limestone filler and nanosilica), which achieved a compactness of φ = 0.789 and 93.7 MPa for compressive strength. However, at 28 days the result was reversed with compressive strengths of 124.6 and 121.7 MPa, respectively. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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19 pages, 3783 KiB  
Article
Effect of Nano Silica Particles on Impact Resistance and Durability of Concrete Containing Coal Fly Ash
by Peng Zhang, Dehao Sha, Qingfu Li, Shikun Zhao and Yifeng Ling
Nanomaterials 2021, 11(5), 1296; https://doi.org/10.3390/nano11051296 - 14 May 2021
Cited by 53 | Viewed by 3535
Abstract
In this study, the effect of adding nano-silica (NS) particles on the properties of concrete containing coal fly ash were explored, including the mechanical properties, impact resistance, chloride penetration resistance, and freezing–thawing resistance. The NS particles were added into the concrete at 1%, [...] Read more.
In this study, the effect of adding nano-silica (NS) particles on the properties of concrete containing coal fly ash were explored, including the mechanical properties, impact resistance, chloride penetration resistance, and freezing–thawing resistance. The NS particles were added into the concrete at 1%, 2%, 3%, 4%, and 5% of the binder weight. The behavior under an impact load was measured using a drop weight impact method, and the number of blows and impact energy difference was used to assess the impact resistance of the specimens. The durability of the concrete includes its chloride penetration and freezing–thawing resistance; these were calculated based on the chloride diffusion coefficient and relative dynamic elastic modulus (RDEM) of the samples after the freezing–thawing cycles, respectively. The experimental results showed that the addition of NS can considerably improve the mechanical properties of concrete, along with its freezing–thawing resistance and chloride penetration resistance. When NS particles were added at different replacement levels, the compressive, flexural, and splitting tensile strengths of the specimens were increased by 15.5%, 27.3%, and 19%, respectively, as compared with a control concrete. The addition of NS enhanced the impact resistance of the concrete, although the brittleness characteristics of the concrete did not change. When the content of the NS particles was 2%, the number of first crack impacts reached a maximum of 37, 23.3% higher compared with the control concrete. Simultaneously, the chloride penetration resistance and freezing–thawing resistance of the samples increased dramatically. The optimal level of cement replacement by NS in concrete for achieving the best impact resistance and durability was 2–3 wt%. It was found that when the percentage of the NS in the cement paste was excessively high, the improvement from adding NS to the properties of the concrete were reduced, and could even lead to negative impacts on the impact resistance and durability of the concrete. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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15 pages, 3657 KiB  
Article
Towards Ultrahigh Performance Concrete Produced with Aluminum Oxide Nanofibers and Reduced Quantities of Silica Fume
by Scott Muzenski, Ismael Flores-Vivian, Behrouz Farahi and Konstantin Sobolev
Nanomaterials 2020, 10(11), 2291; https://doi.org/10.3390/nano10112291 - 19 Nov 2020
Cited by 17 | Viewed by 2534
Abstract
Ultrahigh performance concrete (UHPC), which is characterized by dense microstructure and strain hardening behavior, provides exceptional durability and a new level of structural response to modern structures. However, the design of the UHPC matrix often requires the use of high quantities of supplementary [...] Read more.
Ultrahigh performance concrete (UHPC), which is characterized by dense microstructure and strain hardening behavior, provides exceptional durability and a new level of structural response to modern structures. However, the design of the UHPC matrix often requires the use of high quantities of supplementary cementitious materials, such as silica fume, which can significantly increase the cost and elevate the production expenses associated with silica fume handling. This paper demonstrates that a fiber-reinforced composite with properties similar to conventional UHPC can be realized with very low quantities of silica fume, such as 1% by mass of cementitious materials. The proposed UHPC is based on reference Type I cement or Type V Portland cement with very low C3A (<1%) that also complies with Class H oil well cement specification, silica fume, small quantities of Al2O3 nanofibers, and high-density polyethylene or polyvinyl alcohol macro fibers. Previous research has demonstrated that nanofibers act as a seeding agent to promote the formation of compact and nanoreinforced calcium silicate hydrate (C-S-H) clusters within the interparticle and nanofiber spaces, providing a nanoreinforcing effect. This approach produces a denser and stronger matrix. This research expands upon this principle by adding synthetic fibers to ultrahigh strength cement-based composites to form a material with properties approaching that of UHPC. It is indicated that the developed material provides improved strain hardening and compressive strength at the level of 160 MPa. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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Review

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25 pages, 4271 KiB  
Review
A Review on the Application of Nanocellulose in Cementitious Materials
by Aofei Guo, Zhihui Sun, Noppadon Sathitsuksanoh and Hu Feng
Nanomaterials 2020, 10(12), 2476; https://doi.org/10.3390/nano10122476 - 10 Dec 2020
Cited by 40 | Viewed by 5094
Abstract
The development of the concrete industry is always accompanied by some environmental issues such as global warming and energy consumption. Under this circumstance, the application of nanocellulose in cementitious materials is attracting more and more attention in recent years not only because of [...] Read more.
The development of the concrete industry is always accompanied by some environmental issues such as global warming and energy consumption. Under this circumstance, the application of nanocellulose in cementitious materials is attracting more and more attention in recent years not only because of its renewability and sustainability but also because of its unique properties. To trace the research progress and provide some guidance for future research, the application of nanocellulose to cementitious materials is reviewed. Specifically, the effects of cellulose nanocrystal (CNC), cellulose nanofibril (CNF), bacterial cellulose (BC), and cellulose filament (CF) on the physical and fresh properties, hydration, mechanical properties, microstructure, rheology, shrinkage, and durability of cementitious materials are summarized. It can be seen that the type, dosage, and dispersion of nanocellulose, and even the cementitious matrix type can lead to different results. Moreover, in this review, some unexplored topics are highlighted and remain to be further studied. Lastly, the major challenge of nanocellulose dispersion, related to the effectiveness of nanocellulose in cementitious materials, is examined in detail. Full article
(This article belongs to the Special Issue Concrete under Nanoscope)
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