Scientific Research and Essays

  • Abbreviation: Sci. Res. Essays
  • Language: English
  • ISSN: 1992-2248
  • DOI: 10.5897/SRE
  • Start Year: 2006
  • Published Articles: 2711

Full Length Research Paper

Influence of nanosilica and a polycarboxylate superplasticizer on the rheological and electrokinetical properties of cement pastes

Madjid Samar
  • Madjid Samar
  • Research Unit, Materials, Processes and Environment (UR/MPE), Faculty of Engineering, University M?Hamed Bougara Boumerdes, Algeria.
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Abdelbaki Benmounah
  • Abdelbaki Benmounah
  • Research Unit, Materials, Processes and Environment (UR/MPE), Faculty of Engineering, University M?Hamed Bougara Boumerdes, Algeria.
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Brahim Safi
  • Brahim Safi
  • Research Unit, Materials, Processes and Environment (UR/MPE), Faculty of Engineering, University M?Hamed Bougara Boumerdes, Algeria.
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Rabia Kheribet
  • Rabia Kheribet
  • Research Unit, Materials, Processes and Environment (UR/MPE), Faculty of Engineering, University M?Hamed Bougara Boumerdes, Algeria.
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Mohammed Saidi
  • Mohammed Saidi
  • Research Unit, Materials, Processes and Environment (UR/MPE), Faculty of Engineering, University M?Hamed Bougara Boumerdes, Algeria.
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  •  Received: 07 June 2014
  •  Accepted: 05 December 2014
  •  Published: 30 December 2014

Abstract

The effect of individual and combined addition of both nanosilica (NS) and polycarboxylate ether plasticizer (PCE) admixtures on cements pastes was studied. The sole incorporation of NS increased the water demand, as proved by the mini-spread flow test. An interaction between NS and hydrated cement particles was observed in fresh mixtures by means of particle size distribution studies, zeta potential measurements and optical microscopy, giving rise to agglomerates. On the other hand, the addition of PCE to a cement paste increased the flowability and accelerated the setting process. PCE was shown to act in cement media as a deflocculating agent, reducing the particle size of the agglomerates through a steric hindrance mechanism. Mechanical strengths were improved in the presence of either NS or PCE, the optimum being attained in the combined presence of both admixtures that involved relevant microstructural modifications, as proved by pore size distributions and SEM observations. The results indicate also the effectiveness of NS and polycarboxylate superplasticizer in producing high packing density and in accelerating the pozzolanic activity to produce more C-S-H gel by consuming calcium hydroxide Ca(OH)2 in order to improve the mechanical properties of cement pastes.
 
Key words: Cement pastes, polycarboxylate plasticizer, nanosilica, optical microscopy, rheological and electrokinetical properties.