SYMPOSIA PAPER Published: 01 January 1996

Alkali-Slag Cements For the Immobilization Of Radioactive Wastes


Alkali-slag cements consist of glassy slag and an alkaline activator and can show both higher early and later strengths than Type III Portland cement, if a proper alkaline activator is used. An examination of microstructure of hardened alkali-slag cement pastes with the help of XRD and SEM with EDAX shows that the main hydration product is C-S-H (B) with low C/S ratio and no crystalline substances exist such as Ca(OH)2, A1(OH)3 and sulphoaluminates. Mercury intrusion tests indicate that hardened alkali-slag cement pastes have a lower porosity than ordinary Portland cement, and contain mainly gel pores. The fine pore structure of hardened alkali-slag cement pastes will restrict the ingress of deleterious substances and the leaching of harmful species such as radionuclides. The leachability of Cs+ from hardened alkali-slag cement pastes is only half of that from hardened Portland cement. From all these aspects, it is concluded that alkali-slag cements are a better solidification matrix than Portland cement for radioactive wastes.

Author Information

Shi, C
Wastewater Technology Centre, Burlington, Ontario, Canada
Day, RL
The University of Calgary, Calgary, Canada
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Developed by Committee: D34
Pages: 163–173
DOI: 10.1520/STP14111S
ISBN-EB: 978-0-8031-5318-9
ISBN-13: 978-0-8031-1443-2