Grantee Research Project Results

Final Report: Increasing Concrete Strength using Biochar-derived Graphene Products for Reduction of Embodied Carbon

EPA Contract Number: 68HERC24C0026
Title: Increasing Concrete Strength using Biochar-derived Graphene Products for Reduction of Embodied Carbon
Investigators: Richard, Anthony R
Small Business: Acadian Research & Development LLC
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2023 through May 30, 2024
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2024) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR)

Description:

The purpose of the research in this project is to demonstrate the use of wood-derived graphene oxide (GO) products as concrete additives to significantly improve strength, which translates to a reduction in materials needed for construction and therefore a reduction in embodied carbon. The difference with the GO material proposed for this project is that it is produced via a newly developed low-cost method and is derived from wood instead of graphite, which has no domestic production, or coal, which has environmental implications associated with mining.

The project consists of three parts: materials synthesis, materials characterization, and testing in concrete. For materials synthesis the base feedstock material is wood which is pyrolyzed to produce biochar, and then converted to GO. GO is the oxidized version of graphene, and high temperature annealing of GO under inert atmosphere produces rGO through a thermal reduction process, which removes a portion of the oxygen. The biochar examined in this project was produced at two temperatures, 600 and 900°C.

Materials were characterized to determine if the GO synthesis process was successful, and to examine the effect of biochar synthesis temperature on concrete additive performance. These characterizations examine chemical and physical properties and include scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and N₂ sorption analysis.

To examine the performance of the GO and rGO additives in concrete, mixes were produced with contents of 0%, 0.05%, and 0.5% of cement by weight. The concrete was examined for strength via compression, flexural, and tensile testing.

Summary/Accomplishments (Outputs/Outcomes):

The results show successful conversion of biochar to GO (increased oxygen groups and lattice defects, increased order in structure), and successful reduction of GO to rGO (loss of oxygen, further defects, layer contraction). Increase in production scale was also successful.

The addition of GO marginally increases the long-term compressive strength, while rGO shows promise for enhancing the long-term compressive strength, achieving a 16.4% increase at 28 days. The addition of GO or rGO at the investigated concentrations (0.05 wt% and 0.5 wt%) appears to have minimal influence on the flexural and tensile strengths of concrete, while the addition of GO and rGO increases the modulus of elasticity.

Conclusions:

There is excellent commercial potential for the GO additives produced in this project. The low-cost nature of the product means feasibility for large scale applications with concrete ($617 billion global market), and process improvements have lowered production costs even further.