2024-03-28T18:44:49Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/513752017-10-10T06:57:27Zcom_10261_29879com_10261_3col_10261_29882
DIGITAL.CSIC
author
García Calvo, José Luis
author
Alonso, C.
author
Hidalgo, A.
author
Fernández Luco, L.
2012-06-12T10:52:54Z
2012-06-12T10:52:54Z
2011
http://hdl.handle.net/10261/51375
Cementitious materials play an important role in the structural stability
and integrity of a purpose built repository for the geological disposal of high level
waste (HLW). However, the expected generation of an alkaline plume from the
concrete by the ingress of groundwater would have detrimental effects on the intended
use of a bentonite buffer. To limit this risk, low-pH cementitious materialss
are being developed to have a target pH < 11 corresponding to the upper stability
limit of bentonite. The research on low-pH cementitious materials is being addressed
from different approaches depending on the type of cement used, emphasising
the use of Ordinary Portland Cements (OPC based) and Calcium Aluminates
Cements (CAC based), in both cases with high mineral admixtures contents
with high silica percentage in their composition. It is well known that the high
mineral admixtures contents used in the low-pH binders significantly modify the
microstructure and the pore fluid of these cementitious materials. Therefore, once
the short-term hydration of these special cements is known, this paper deals with
the modifications generated in the chemical composition of the pore solutions of
low-pH cement pastes based on CAC and in their solid phases after 2 years of hydration.
The results show a high stability of the solid phases formed in the shortterm
(90 days). This paper also deals with the resistance of these low-pH cementitious
materials to long term ground water aggression using two types of aggressive
agents: deionised water and ground water from the real site of Äspö (Sweden).
Low-pH concretes based on CAC plus silica fume have been evaluated. This evaluation
implies the study of the modifications made in the microstructure of lowpH
concretes due to their exposure to a constant water flow and in the chemical
composition of the leaching fluid.
eng
closedAccess
Low pH cements based on CAC for underground repositories of HLW: long-term hydration and resistance against ground water aggression
comunicación de congreso
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