TY - JOUR
T1 - Retention of strontium in high- & low-pH cementitious matrices – OPC vs. model systems
AU - Shiner, Matan E.
AU - Klein-BenDavid, Ofra
AU - L'Hôpital, Emilie
AU - Dauzères, Alexandre
AU - Neji, Mejdi
AU - Teutsch, Nadya
AU - Peled, Alva
AU - Bar-Nes, Gabriela
N1 - Funding Information:
This study was supported by the Israel Atomic Energy Commission (IAEC), IRSN and by the High-tech, Bio-tech and Chemo-tech scholarship of Kreitman School of Advanced Research of Ben-Gurion University of the Negev . The authors would like to acknowledge Haim Furman and Yair Alex Singer for their technical and experimental assistance as well as the two reviewers for their constructive and insightful comments.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Strontium can be found in low/intermediate level radioactive waste streams, often solidified by Ordinary Portland Cement (OPC) matrices. Amorphous silica is added to improve wasteform performance, leading to low-pH systems. Our aim is to identify the phases controlling strontium immobilization in OPC matrices. The novelty of this work resides in combination between two approaches: 1) Comparing OPC systems to model systems based on alite, yielding matrices containing only major phases, emphasizing the relative role of minor phases; 2) Comparing high- & low-pH pastes. Pastes were characterized using calorimetry, XRD, DTG, SEM/EDS and porosimetry. Leaching experiments were conducted to study Sr retention and diffusivity. Strontium diffusivities in low-pH pastes are lower with respect to high-pH equivalents, despite their higher porosities, due to preferred Sr sorption to low Ca/Si C-S-H. OPC pastes show better Sr retention relative to model systems, suggesting that minor phases (like ettringite and AFm) improve Sr retention.
AB - Strontium can be found in low/intermediate level radioactive waste streams, often solidified by Ordinary Portland Cement (OPC) matrices. Amorphous silica is added to improve wasteform performance, leading to low-pH systems. Our aim is to identify the phases controlling strontium immobilization in OPC matrices. The novelty of this work resides in combination between two approaches: 1) Comparing OPC systems to model systems based on alite, yielding matrices containing only major phases, emphasizing the relative role of minor phases; 2) Comparing high- & low-pH pastes. Pastes were characterized using calorimetry, XRD, DTG, SEM/EDS and porosimetry. Leaching experiments were conducted to study Sr retention and diffusivity. Strontium diffusivities in low-pH pastes are lower with respect to high-pH equivalents, despite their higher porosities, due to preferred Sr sorption to low Ca/Si C-S-H. OPC pastes show better Sr retention relative to model systems, suggesting that minor phases (like ettringite and AFm) improve Sr retention.
KW - CS
KW - Leaching
KW - Low-pH cement
KW - Portland cement
KW - Radioactive waste
KW - Strontium immobilization
UR - http://www.scopus.com/inward/record.url?scp=85119337051&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2021.106659
DO - 10.1016/j.cemconres.2021.106659
M3 - Article
AN - SCOPUS:85119337051
SN - 0008-8846
VL - 152
JO - Cement and Concrete Research
JF - Cement and Concrete Research
M1 - 106659
ER -