Nano-Enabled Multifunctional Concrete for Transportation Infrastructure

Despite several decades of studies, concrete bridges, highways and infrastructures still significantly suffer from fracture, deterioration and external chemical attacks with maintenance costs that amount to multi-billion dollars annually. To address the above critical needs, this project developed a new class of ultra-high performance, multifunctional concrete using emerging two-dimensional (2D) materials. The core strategy lies in mixing ultra-thin exfoliated nanosheets of 2D materials such as hexagonal boron nitride, hBN, as small as few atoms in thickness, in the bulk concrete. hBN exhibits several exotic properties (ultrahigh mechanical and thermal properties, chemical inertness, hydrophobicity, etc) that are highly desirable for a complex matrix such as concrete. These features, combined with the double surface area per mass of hBN sheets- compared to conventional 1D fibers - can act as template (seeds) to regulate the hydration processes and maximum contact between the sheets and the matrix, thereby providing an effective reinforcement from the bottom up. The overarching goal of this project was to study and identify the optimum experimental conditions and parameters for delivering the maximum mechanical properties and durability in hBN/concrete while economically and commercially being viable. The research team studied several different routes to investigate the degree of exfoliation and reduction in size of hBN (to increase surface area) as well as their functionalization and water solubility in effectively mixing them in concrete. They synthesized various concrete coupons with variety of weight percentages of 2D materials. Notable among results are the compressive strength of the concrete cylinders that can increase by >71%, with only a very small fraction of the 2D materials. Furthermore, the authors found the tensile strength of the concrete samples increases by >100%. The measured durability properties of the concrete samples also showed ~35% increase, compared to the control sample devoid of hBN. The origin of the improved properties stem from two key factors: 1) Ultrahigh surface area of hBN (ideally >2200 m2 /g for mono layer 2D materials), which effectively connect and bridge several phase of the concrete matrix, and 2) a charge transfer from Boron of hBN to Oxygen of Silicate groups in the concrete matrix, creating strong electrostatic bonds between 2D materials and the matrix. Following discussions with TxDOT and implementation requirements, they determined a patch/repair job on a surface of a road/highway to be a good starting point for field testing. Upon consultation with TxDOT, they examined the compatibility of the formula with common accelerators such as CaCl2 and found no negative cross-effect between their technology and common accelerators while exhibiting compressive strength of 1800 psi in only ~5 hours, making the technology suitable for rapid construction and/or maintenance in transportation applications.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References;
  • Pagination: 28p
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01723879
  • Record Type: Publication
  • Report/Paper Numbers: NCHRP IDEA Project 197
  • Files: TRIS, TRB, ATRI
  • Created Date: Nov 27 2019 4:16PM