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Microstructural study of Portland cement additivated with Nanomaterials

Abstract:

The present study shows the experimental results about the physical properties and microstructural changes of Portland cement with γ and α alumina nanoparticles. All alumina samples were synthesized from an industrial byproduct. Cement matrix was additivated with nanoalumina at different quantities (from 0.5% up to 1% by weight of cement). Porosimetry and gas permeability tests on the hardened cementitious systems were performed. Results showed a 40% decrease in permeability for γ-Al2O3 system. The surface analysis of the γ-Al2O3-based cementitious specimens was carried out, resulting in a substantial decreasing of their surface area and pore volume in comparison with the reference material. Additionally, α-Al2O3-based cement systems showed less proportion of amorphous CSH gels and portlandite crystals were predominant. In contrast, γ-Al2O3-based composite materials exhibit well defined etringite crystals (needle-like structures), further remarkable changes in the CSH gel morphology, impacting on the macroscopic mechanical properties.