The Role of Surface Area and Compacity of Nanoparticles on the Rheology of Cement Paste 25.3

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Title: The Role of Surface Area and Compacity of Nanoparticles on the Rheology of Cement Paste 25.3

Author(s): Oscar A. Mendoza Reales, Emílio C. C. M. Silva, Maria D. M. Paiva, Pedro Duda, and Romildo Dias Toledo Filho

Publication: Special Publication

Volume: 320

Issue:

Appears on pages(s): 25.1-25.14

Keywords: nanoparticles; rheology; surface area; viscosity; yield stress

Date: 8/1/2017

Abstract:
Nanoparticles have a great influence on the rheology of cement matrices due to their inherent physical and chemical properties. This work quantifies the relation between matrix rheology and surface area of nanoparticles (carbon nanotubes, nanosilica and nanoclay), by comparing them with the effects of some equivalent microparticles (microsilica and metakaolin). Class G cement pastes blended with micro- or nanoparticles were prepared using a water-to-cementitious material ratio of 0.45 and a viscosity modifying agent to prevent segregation and settlement. Static yield stress, dynamic yield stress, and plastic viscosity were determined to characterize the rheology. The first was measured directly, while the other two were obtained by fitting a Bingham model to the descending portion of a flow curve. It was found that micro- and nano- particle substitutions of similar composition and surface area have similar effects on the rheological parameters, indicating that the influence of nanoparticles is mainly governed by their specific surface area.