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Development of an electro-chemical accelerated ageing method for leaching of calcium from cementitious materials

Arezou Babaahmadi (Institutionen för bygg- och miljöteknik, Byggnadsteknologi) ; Luping Tang (Institutionen för bygg- och miljöteknik, Byggnadsteknologi) ; Zareen Abbas ; Thomas Zack ; Per Mårtensson
Materials and Structures (1359-5997). Vol. 49 (2016), 1-2, p. 705-718.
[Artikel, refereegranskad vetenskaplig]

To facilitate the long term durability predictions of nuclear waste repositories, acceleration methods enhancing calcium leaching process from cementitious materials are needed, even though mechanisms not necessarily comparable to those predominant in a natural leaching process may be developed. In the previously published acceleration methods the samples are very small, which limits further physical or mechanical tests. In this paper, a new acceleration method based on electro-chemical migration is presented. The method although not driven with the same kinetics as in natural leaching, was designed in such a way that unnecessarily destructive by-effects could be minimized while promoting a higher leaching rate for a sample size suitable for further testing the mechanical and physical properties. It is shown that approximately 1x10^6 C of electrical charge per paste specimen of size Ø50 x 75 mm (approximately 230 g) is required to leach out the total amount of Portlandite. The chemical and mineralogical properties of leached samples are characterized by various techniques. It is concluded that aged samples are comparable to those leached in a natural leaching process as both are characterized by a layered system comprising an unaltered core delineated by total dissolution of Portlandite followed by a progressive decalcification of the calcium silicate hydrate gel.

Nyckelord: Acceleration method, Calcium leaching, Service life, Mineralogical properties, Nuclear waste management



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Denna post skapades 2015-01-26. Senast ändrad 2016-11-02.
CPL Pubid: 211526

 

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Institutioner (Chalmers)

Institutionen för bygg- och miljöteknik, Byggnadsteknologi
Institutionen för kemi och molekylärbiologi (GU)
Institutionen för geovetenskaper (GU)

Ämnesområden

Building Futures
Materialvetenskap
Samhällsbyggnadsteknik
Materialteknik

Chalmers infrastruktur