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Applicability of Nordic clays as SCM

Author(s): Harald Justnes, Tone Østnor, Serina Ng
Paper category: Proceedings
Book title: Proceedings of the International RILEM Conference
Materials, Systems and Structures in Civil Engineering 2016
Segment on Concrete with Supplementary Cementitious Materials
Editor(s): Ole M. Jensen, Konstantin Kovler and Nele De Belie
e-ISBN: 978-2-35158-179-7
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 344 - 353
Total Pages: 10
Language : English

Abstract: Nordic clays are usually low in kaolin and rich in illite and smectite, unlike clays in tropical zones that are rich in kaolin. It has been shown that Nordic clays also perform well as SCMs in spite of their low kaolin content when calcined carefully. Furthermore, Nordic clays are also usually contaminated with inert quartz particles that does not seem to hamper the performance too much as they may potentially act as fillers. Sometimes the clays are contaminated with calcium carbonate that actually can be beneficial as it may react with pozzolanic products to form calcium carboaluminate hydrates leading to extra bound water and densification of the microstructure and thereby also increased strength. The performance of three Nordic clays as SCMs is documented by strength data of mortars when these calcined clays are partly replacing cement. For more clarity on the pozzolanic mechanism, one of the clays – 'marl' was studied in greater details. The results are discussed in terms of microstructural features as studied by XRD, thermal analysis and scanning electron microscopy. To further elucidate their applicability, the clays used are dug directly out of the ground without any purification prior to calcination. Social aspects of using "quick clay" that otherwise have to be removed before land exploration is also briefly discussed.

Online publication : 2016
Publication type : full_text
Public price (Euros) : 0.00

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