Pine Sawmill Waste-Derived Graphene Derivatives for Cementitious Composites

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Chemistry

Background:

• Conventional graphene oxide (GO) and reduced graphene oxide (rGO) are typically synthesized from graphite.
• There is a growing need for sustainable and cost-effective alternatives derived from renewable resources.
• Pinewood waste biomass presents a viable source for producing biochar-based graphene materials.

Purpose of the Study:

• To investigate the synthesis of GO and rGO from pinewood waste biomass via pyrolysis.
• To evaluate the influence of these biochar-based graphene materials (BCGO and BCrGO) on cementitious composites.
• To compare their performance against conventionally synthesized GO and rGO as cement additives.

Main Methods:

• Pyrolysis-temperature-controlled synthesis of graphene materials from pinewood biochar at 450, 600, and 900 °C.
• Incorporation of synthesized GO and rGO into cement pastes and concrete at varying dosages (0.05% and 0.5% BWOC).
• Comprehensive material characterization, hydration behavior analysis, microstructural investigation, and mechanical performance testing (compressive, flexural, tensile strength, modulus of elasticity).

Main Results:

• Successful formation of partially layered carbon structures from biochar.
• Accelerated hydration kinetics and enhanced hydration product development in cement pastes without altering cement chemistry.
• Strengthened Si-O-Si and Si-O-Ca bonds, denser microstructure, and improved interfacial bonding observed.
• Up to 10% increase in compressive strength, 9% in flexural/tensile strength, and a significant 55% enhancement in the modulus of elasticity in concrete.
• No significant changes in concrete density, pH, or Poisson's ratio.

Conclusions:

• Renewable biochar-based GO and rGO can effectively replace conventional graphite-derived materials in cementitious composites.
• These sustainable additives enhance hydration, microstructure, and mechanical properties, particularly the modulus of elasticity.
• The pyrolysis temperature influences the resulting graphene material's effectiveness.
• Biochar-based graphene materials offer a promising route for developing high-performance, sustainable construction materials.