Functionalization of Carbon Nanotubes into Materials with High Compressive Strengths

Cement-based materials with desirable compressive strength, moisture resistance, life-cycle economy and energy-efficiency are commonly used in civilian and military infrastructure. Their low tensile strength, brittleness and instability in aggressive environments are drawbacks which can be partly overcome by fiber reinforcement. When compared with conventional (micro-scale) fibers, graphite nanomaterials (nanotube, nanofiber and nanoplatelet) offer superior mechanical/physical attributes and distinct geometric features. The Phase I project developed minimally invasive non-covalent/covalent functionalization techniques and simple refinements of matrix to greatly improve the dispersion, interfacial interaction and reinforcement efficiency of graphite nanomaterials in cement-based matrices. Significant gains in flexural strength and energy absorption, abrasion and impact resistance, and barrier qualities were realized with <0.1 vol.% functionalized nanomaterials. Statistical analysis of results confirmed the superior reinforcement efficiency of functionalized nanomaterials over carbon fibers. Theoretical and microstructural investigations indicated that significant debonding and frictional pullout energy dissipation over the large surface area of nanomaterials, and highly tortuous diffusion and crack propagation paths explain the distinct reinforcing qualities of functionalized nanomatrials. The proposed Phase II project will build upon the promising Phase I research outcomes towards enhanced functionalization and dispersion of graphite nanomaterials, and optimization, comprehensive laboratory evaluation, modeling and design, industrial-scale production, and competitive market evaluation of cement-based materials and products reinforced with functionalized graphite nanomaterials.