As the concrete industry continues to prioritize sustainability towards the goal of achieving net zero by 2050, the use of nanomaterials (such as nanosilica, nanolimestone, carbon nanofibers, carbon nanotubes, graphene nanoplatelets, etc.) in concrete offers promising avenues in this direction. This technical session will explore the latest advancements and challenges in leveraging nanomaterials to improve the sustainability of concrete. Topics will include the role of nanomaterials in enhancing the properties of concrete (strength, durability, etc.) as well as their potential to reduce the overall environmental footprint of concrete. The presentations will include laboratory evaluation, practical implementation, lifecycle assessment, and future directions of nanomaterial-enhanced concrete for sustainable infrastructure development.
Learning Objectives:
(1) Describe the use of nanomaterials as a strategy to improve concrete sustainability;
(2) Investigate the potential environmental benefits with a detailed lifecycle analysis;
(3) Report on research progress and key challenges in this area;
(4) Formulate insights into practical implementation strategies.
This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.
Morphological, Microstructural, and Mechanical Properties of Highly-Ordered C–S–H Regulated by Cellulose Nanocrystals (CNCs)
Presented By: Weina Meng
Affiliation: Stevens Institute of Technology
Description: For decades, the limited elasticity and weak flexural strength of cementitious materials have posed enduring challenges. Addressing these issues has become critically urgent in modern society, given the escalating demand for high-performance and sustainable construction materials. Calcium-silicate-hydrate (C-S-H), as the main hydration product of cement, plays important roles in gaining the mechanical performance and durability of cementitious materials. However, random growth of the microstructures of C-S-H largely compromises the mechanical properties and durability. This paper proposes to utilize environmentally friendly cellulose nanocrystals (CNCs) to modify the microstructures of C-S-H. This research investigates the effect of CNCs on the morphological, microstructural, and mechanical properties of C-S-H. The results showed that CNCs can effectively mitigate the agglomeration of C-S-H and generate C-S-H/CNC nanocomposites with highly ordered, layered, and dense microstructures. The C-S-H and CNCs in the C-S-H/CNC nanocomposites had strong interactions through hydrogen bonds and calcium ion coordination bonds. The strong interactions and ordered microstructures enable C-S-H/CNCs nanocomposites to achieve high modulus (56 GPa) and high strength (83 MPa). This represents a substantial increase, with the modulus being 2.9 times greater and the strength a notable 21 times higher than that of pure C-S-H (19 GPa and 4 MPa). This approach eliminates the necessity for the calcination of cement raw materials, leading to over 50 wt% reduction in carbon emissions. Furthermore, these C-S-H-based nanocomposites hold great promise for significantly enhancing the sustainability of concrete materials in the future.
In-situ Dispersion of Nano-CaCO3 in Concrete: A Sustainable Approach
Presented By: Yogiraj Sargam
Affiliation: CarbonCure Technologies
Description: The use of nano-CaCO3 in cementitious systems has been widely recognized for their benefits, such as promoting cement hydration by providing nucleation sites, enhancing particle packing, immobilizing free water, reducing ITZ porosity, and improving mechanical performance and durability. Despite these benefits, challenges such as agglomeration and uneven dispersion hinder their widespread adoption. Therefore, identifying cost-effective dispersion methods to address these challenges is crucial. This presentation will explore a promising solution for in-situ dispersion of nano-CaCO3 using CO2 mineralization. The methodology involves injecting captured CO2 into fresh concrete during mixing, leading to the formation of uniformly dispersed nano-CaCO3 particles without the need for external dispersants. Additionally, the resulting concrete can be optimized to contain lower cement content, thereby reducing its overall environmental impact. This approach effectively addresses two concerns simultaneously: achieving better nanoparticle dispersion and decreasing the carbon footprint of concrete production.
Carbon Capture and Utilization of Nano-reinforced Cementitious Composites
Presented By: Rohitashva Singh
Affiliation: University of Texas Arlington
Description: One of the most common ways of reducing the CO2 footprint of concrete is by replacing the cement with supplementary cementitious materials. However, this is not sufficient to reach carbon neutrality. Carbon Capture and Utilisation/Storage has a promising potential of reducing the CO2 footprint of concrete by 40%. Blended cement with low calcium content has a reduced capacity to bind CO2 and the addition of small amounts of dispersed nanomaterials can significantly improve the CO2 sequestration potential of the composite. Incorporation of 0.6 wt% nano-SiO2 enhances the carbonation reaction and results in a 20% increase in CO2 uptake capacity when compared to plain mortar. In addition, formation of aragonite is promoted, and the compressive strength exhibited a significant increase of 45%. Carbonation curing of precast concrete products such as cellulose fibreboards provides both accelerated hydration and carbon sequestration. The addition of 0.1 wt% of cellulose nanofibers provides a channelling effect in the matrix which allows for faster diffusion of CO2 in the matrix resulting in a 10% and 66% increase in compressive strength and flexural strength at 28 days, respectively. More than 20% of the carbonates formed are metastable which make the microstructure denser by reducing the volume of pores and the average pore diameter.
Enhancing Cementitious Composites with Ready-to-Use Liquid Hydrous Bio-Graphene Oxide Admixture
Presented By: Mayra Grazia
Affiliation: Alter Biota Inc.
Description: Optimization of concrete mixtures with strength enhancing graphene oxide (GO) nanomaterials presents a potentially efficient way to enhancing strength and achieving NetZero goals. Various studies have demonstrated that GO can enhance the microstructure, permeability, and mechanical properties. However, challenges associated with the homogeneous incorporation of GO into the ready-mix concrete matrix may impact concrete performance. In this context, hydrous Bio-Graphene Oxide (deltaC), a stabilized water-based suspension of biochar derived from forestry by-products has been proposed as a scalable carbon negative admixture. This study investigates the influence of different dosages of deltaC solids (ranging from 1.5 to 3.5% b.w.c.) on concrete mixtures, analyzing both fresh and hardened state properties. Experimental results from slump and air content tests confirm that deltaC may enhance workability while also improving compressive strength. Additionally, studies with 5% cement reduction developed with deltaC showed comparable fresh and hardened state performance. By incorporating deltaC, concrete mixtures can achieve improved fresh and hardened state properties, enhance sustainability through carbon storage, and contribute to advancing NetZero construction goals.
Highly Resilient Sustainable Concrete Using Low Carbon Calcined Clay-Based Binders and Nanomaterials
Presented By: Panagiotis Danoglidis
Affiliation: University of Texas At Arlington
Description: The objective of this presentation is to design sustainable concrete by replacing ordinary Portland cement with low-carbon calcined clay-based binders and reinforcing it with nanomaterials. This is a promising way for developing highly resilient concrete, with at least 2x increased modulus of elasticity and tensile strain energy absorption capability. The output of the proposed study will help promoting low-cost pathways for developing low embodied carbon concrete with significantly reduced carbon footprint over OPC concrete throughout the entire life cycle.
Graphene's Impact on C-S-H and Concrete Sustainability
Presented By: Hunain Alkhateb
Affiliation: The University of Mississippi
Description: This research examines the microstructural and crystalline features of graphene-reinforced calcium silicate hydrate (C-S-H) composites. We aim to elucidate how varying the content of Graphene Nanoplatelets (GnPs) and the surrounding pH level influences the growth and arrangement of C-S-H crystals. C-S-H crystals are critical in the material's overall properties as the primary hydration products in any cement or concrete. This research will present our findings on how GnPs influence C-S-H crystallization through a comprehensive analysis of multiscale physiochemical interactions. Understanding these interactions is crucial for developing more sustainable concrete with enhanced properties.