Efficiency of Calcined Clay in Cementitious Systems


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Title: Efficiency of Calcined Clay in Cementitious Systems

Author(s): Nancy Beuntner, Klaus Rapp, and Karl-Christian Thienel

Publication: Special Publication

Volume: 289


Appears on pages(s): 1-12

Keywords: calcined clay; cement type; SEM; type II addition; XRD

Date: 9/14/2012

Lias Delta clay was calcined on production scale in a rotary kiln. Subsequently it was ground and tested as type II addition in combination with three different cements. Workability and strength development were investigated. These physical tests were accompanied by microstructural analysis of the calcined clay and cement paste made with and without the addition of calcined clay. After a hydration of 28 d major differences could neither be detected by means of SEM nor by XRD in the mineral phases present in mixes made with or without. Only the content of portlandite was reduced due to the pozzolanic reaction of the calcined clay. Parallel tests using marble flour for comparison ruled out that strength increase was due to physical filler effects.