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'Buffer' effects of natural zeolites in blended cements

Ruben Snellings UGent (2012) Concrete repair, rehabilitation and retrofitting III. p.1404-1409
abstract
One of the primary sources of natural supplementary cementitious materials are natural zeolite deposits. Natural zeolites present interesting potential both in terms of pozzolan reactivity and availability. Additionally to being consumed in the pozzolanic reaction, the unreacted zeolite fraction interacts with the cement pore solution and the internal cement environment as a water regulator and cation exchanger. Zeolites can reversibly adsorb and release large amounts of water up to 20% of their weight or more. The uptake of water depends on the availability of water in the surrounding environment. The initial expansion of the zeolite lattice parameters as observed by in situ XRD measurements during the hydration of blended cements show that zeolites respond to the introduction of liquid water by adsorbing water into the zeolite microporous framework. In this manner, the effective water/cement ratio and the macroporosity of the system are reduced. Subsequently, the water contained in the zeolites will be released when the latter are consumed in the pozzolanic reaction or when the availability of water in the binder starts to drop. In this respect, zeolites can be considered as water carriers that gradually liberate their water over the hydration period to promote the completion of the hydration reactions. Natural zeolites also thoroughly affect the pore solution chemistry of blended cements. Chemical analysis (AAS and ICP-OES) of the pore solutions in a range of zeolite blended cements show that the addition of zeolites generally increases alkali, Si and Al levels and decreases Ca concentrations in the pore solution. It was observed that the evolution of the pore solution is considerably affected by the zeolite type. The alkali concentration in the contact fluid is affected by the extra-framework cation content and the cation exchange characteristics of the zeolite. Most common natural zeolites (i.e. heulandite-clinoptilolite, mordenite, phillipsite, chabazite) selectively take up K and release Na and Ca to the pore solution.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
in
Concrete repair, rehabilitation and retrofitting III
editor
Mark G Alexander, Hans-Dieter Beushausen, Frank Dehn and Pilate Moyo
pages
1404 - 1409
publisher
CRC Press
place of publication
Leiden, The Netherlands
conference name
3rd International conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR -2012)
conference location
Cape Town, South Africa
conference start
2012-09-03
conference end
2012-09-05
ISBN
9780415899529
language
English
UGent publication?
yes
classification
C1
copyright statement
I have transferred the copyright for this publication to the publisher
VABB id
c:vabb:339714
VABB type
VABB-5
id
2984808
handle
http://hdl.handle.net/1854/LU-2984808
date created
2012-09-11 13:32:44
date last changed
2012-09-14 13:22:06
@inproceedings{2984808,
  abstract     = {One of the primary sources of natural supplementary cementitious materials are natural zeolite deposits. Natural zeolites present interesting potential both in terms of pozzolan reactivity and availability. Additionally to being consumed in the pozzolanic reaction, the unreacted zeolite fraction interacts with the cement pore solution and the internal cement environment as a water regulator and cation exchanger. Zeolites can reversibly adsorb and release large amounts of water up to 20\% of their weight or more. The uptake of water depends on the availability of water in the surrounding environment. The initial expansion of the zeolite lattice parameters as observed by in situ XRD measurements during the hydration of blended cements show that zeolites respond to the introduction of liquid water by adsorbing water into the zeolite microporous framework. In this manner, the effective water/cement ratio and the macroporosity of the system are reduced. Subsequently, the water contained in the zeolites will be released when the latter are consumed in the pozzolanic reaction or when the availability of water in the binder starts to drop. In this respect, zeolites can be considered as water carriers that gradually liberate their water over the hydration period to promote the completion of the hydration reactions. Natural zeolites also thoroughly affect the pore solution chemistry of blended cements. Chemical analysis (AAS and ICP-OES) of the pore solutions in a range of zeolite blended cements show that the addition of zeolites generally increases alkali, Si and Al levels and decreases Ca concentrations in the pore solution. It was observed that the evolution of the pore solution is considerably affected by the zeolite type. The alkali concentration in the contact fluid is affected by the extra-framework cation content and the cation exchange characteristics of the zeolite. Most common natural zeolites (i.e. heulandite-clinoptilolite, mordenite, phillipsite, chabazite) selectively take up K and release Na and Ca to the pore solution.},
  author       = {Snellings, Ruben},
  booktitle    = {Concrete repair, rehabilitation and retrofitting III},
  editor       = {Alexander, Mark G and Beushausen, Hans-Dieter and Dehn, Frank and Moyo, Pilate},
  isbn         = {9780415899529},
  language     = {eng},
  location     = {Cape Town, South Africa},
  pages        = {1404--1409},
  publisher    = {CRC Press},
  title        = {'Buffer' effects of natural zeolites in blended cements},
  year         = {2012},
}

Chicago
Snellings, Ruben. 2012. “‘Buffer’ Effects of Natural Zeolites in Blended Cements.” In Concrete Repair, Rehabilitation and Retrofitting III, ed. Mark G Alexander, Hans-Dieter Beushausen, Frank Dehn, and Pilate Moyo, 1404–1409. Leiden, The Netherlands: CRC Press.
APA
Snellings, R. (2012). “Buffer” effects of natural zeolites in blended cements. In M. G. Alexander, H.-D. Beushausen, F. Dehn, & P. Moyo (Eds.), Concrete repair, rehabilitation and retrofitting III (pp. 1404–1409). Presented at the 3rd International conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR -2012), Leiden, The Netherlands: CRC Press.
Vancouver
1.
Snellings R. “Buffer” effects of natural zeolites in blended cements. In: Alexander MG, Beushausen H-D, Dehn F, Moyo P, editors. Concrete repair, rehabilitation and retrofitting III. Leiden, The Netherlands: CRC Press; 2012. p. 1404–9.
MLA
Snellings, Ruben. “‘Buffer’ Effects of Natural Zeolites in Blended Cements.” Concrete Repair, Rehabilitation and Retrofitting III. Ed. Mark G Alexander et al. Leiden, The Netherlands: CRC Press, 2012. 1404–1409. Print.