Subject matter

Recent years have seen significant interest in research and advancement of the use of carbon-based nanomaterials as nano-additives in cement-based materials to enhance their performance, including their mechanical properties, durability, and functional response. Carbon-based nanomaterials include a wide range of carbon structures (carbon allotropes) and their carbon derivatives and are classified as being 0D (carbon dots and carbon onions), 1D (carbon nanotubes and nanofibers), 2D (graphene nanosheets, graphene nanoplatelets, and multilayer graphene), or 3D (graphite) on the basis of their dimensionality (i.e., aspect ratio). Carbon-based nanomaterials have shown to improve strength, ductility, and fracture resistance; reduce cracking; decrease permeability; and increase durability of cement-based materials, while providing innovative properties such as electrical and thermal conductivity. In addition, the use of carbon-based nanomaterials can reduce the amount of material needed to achieve structural load specifications. Therefore, nanocarbon modified cementitious matrices can lead to more durable, sustainable, and environmentally friendly infrastructure materials and have the potential to be increasingly used as construction materials. Furthermore, with the advent of additive manufacturing and digital fabrication (i.e., 3D printing) of concrete, carbon-based nanomaterials are likely to play an important role as internal reinforcements to improve printability, strength, and durability of the printed concrete structure.

The purpose of this new RILEM Technical Committee (TC) is to compile available information and knowledge on the use of carbon-based nanomaterials in cementitious matrices and results of studies with respect to the effect of carbon-based nanomaterial addition on the material properties in fresh and hardened states. Progress in the production and incorporation of different structural forms of carbon-based nanomaterials; dispersion methods and assessment of dispersion within the cementitious matrix; reinforcing ability of carbon-based nanomaterials; influence of carbon-based nanomaterials on the rheology, hydration, transport, mechanical, and smart properties of cementitious matrices; and laboratory to field applications will be reviewed. It is expected that the role of carbon-based nanomaterials in cementitious matrices and their practical usage and application in construction materials will be more emphasized to the scientific community and the concrete and construction industry. A RILEM TC on this topic will allow for scientific exchanges between researchers and among the research community and practitioners and for the definition of a common framework in the use of carbon-based nanomaterials in cementitious matrices and in evaluating the characteristics and multiscale performance of nanocarbon modified cementitious matrices.

Limits of scope

The focus of the TC will be on all structural forms (allotropes) of carbon-based nanomaterials in portland cement-based binder systems and their effect on the cementitious matrix properties in fresh and hardened states.

Terms of reference

The timeframe of this new RILEM TC is five (5) years, starting Fall 2021. The proposed timeline of the TC activities is as follows:

Years 1-5: Comprehensive literature review of the available technical information and knowledge and development of a state-of-the-art report on investigations and field applications of carbon-based nanomaterials in cementitious matrices.

Years 2-3: Planning and organization of an international workshop on carbon-based nanomaterials in cementitious matrices.

Years 4-5: Development of technical guidelines/recommendations for designing cementitious composites with carbon-based nanomaterials and help implementation of nanocarbon modified cementitious matrices in concrete construction.

Members will include representatives from academia, research centers, and industry from across North America, Europe, and Asia and will be recruited based on their interest and experience with carbon-based nanomaterials in cementitious matrices. It is expected that 15-20 members will contribute.

The work of the TC will be based on information available in the literature and experiences from the committee members. No experimental work is planned to be performed during the timeframe of the TC. However, a potential outcome of the TC could be recommendations for more detailed verifications of mix designs and reproducibility of mechanical properties through inter-laboratory testing and evaluation.

A state-of-the-art report summarizing the available information and knowledge in the area and the definition of a common framework will provide a solid reference for further research and guiding material manufacturers and the concrete and construction industry in utilizing carbon-based nanomaterials in concrete construction.

Detailed working programme

The goals of the proposed TC are to (i) assemble and evaluate research data, including knowledge of all participating members on carbon-based nanomaterials in cementitious matrices and compile the information into a state-of-the-art-report; (ii) develop recommendations for designing cementitious composites with carbon-based nanomaterials and implementation in concrete construction; (iii) provide a balanced view on nanocarbon modified cementitious matrices; and (iv) exchange and disseminate knowledge through the organization of an international workshop on carbon-based nanomaterials in cementitious matrices. The development of the state-of-the-art report will be ongoing for the entire duration of the committee. The amount of information available in the literature is extensive.

The work of the TC will be organized into the following working groups (WG). The WG topics described below are preliminary and will be further defined by each WG. Future trends as well as applications and market solutions, including health and safety and life cycle assessment will considered.

• WG 1 - Fresh properties. Topics will include dispersion and rheology of carbon-based nanomaterials in aqueous solutions and cementitious matrices and interfacial interactions between carbon-based nanomaterials and cementitious matrices for PC-based binders. Important aspects of exfoliation and scaled-up production will be considered.
• WG 2 – Hardened state properties. The focus will be on the effect of 0D, 1D, 2D, and 3D carbon-based nanomaterials on the mechanical, transport, and durability properties of nanocarbon modified cementitious matrices for PC-based binders. The variability in the hardened state properties will be considered.
• WG 3 – Smart properties. The focus will be on electrical, self-sensing, and other functional properties of nanocarbon modified cementitious matrices for PC-based binders.

Potential leaders and contributors of the WG have been identified.