Various durability aspects of calcined Kaolin-blended Portland cement pastes and concretes

The use of calcined clay, in the form of metakaolin (MK), as a pozzolanic constituent for concrete has received considerable attention in recent years, due to the lower CO2 emission of this supplementary cementitious material compared to the production of a classic portland cement. Furthermore, concretes incorporating MK show some improve durability properties. In this paper, the durability of concretes and cement pastes with MK as partial replacement of cement (10 and 25%) has been investigated in comparison with CEM-I materials one. Water porosity, chloride migration and diffusion, electrical resistivity and natural and accelerated carbonation tests have been performed. In addition, microstructural study is performed to better understand the results on the durability indicators. The cement pastes microstructure was characterized not only by usual techniques such as mercury intrusion porosimetry, XRD and TGA-DTA, but also by 29Si and 27Al NMR spectroscopy. For example, Friedel's salt (chemical binding) has been quantified by 27Al NMR spectroscopy and XRD on cement paste. In addition, the progress of the durability properties for various water curing times has been investigated. Results show an evolution of the properties, as a function of the cement replacement degree by MK, such replacement increases durability against chloride penetration but decreases resistance to carbonation. The aluminate phases equilibrium is modified in concrete with metakaolin in comparison with a CEM-I one. Both chemical and physical chloride binding increases with MK replacement. In addition, since portlandite quantity decreases in cement materials with MK, these materials are less resistant to carbonation process for a same exposure condition (time and CO2 concentration).


  • English

Media Info

  • Media Type: Digital/other
  • Pagination: 8p

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Filing Info

  • Accession Number: 01688904
  • Record Type: Publication
  • Source Agency: Institut Francais des Sciences et Technologies des Transports, de l'Amenagement et des Reseaux (IFSTTAR)
  • Files: ITRD
  • Created Date: Dec 18 2018 10:18AM