Title
Cement-waste interactions : hardening self-compacting mortar exposed to gamma radiation Cement-waste interactions : hardening self-compacting mortar exposed to gamma radiation
Author
Faculty/Department
Faculty of Applied Engineering Sciences
Publication type
article
Publication
Oxford ,
Subject
Engineering sciences. Technology
Source (journal)
Progress in nuclear energy. - Oxford
Volume/pages
83(2015) , p. 212-219
ISSN
0149-1970
0149-1970
ISI
000358468300023
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
For the disposal of high level radioactive waste and for attenuation of the emitted radiation, the Belgian supercontainer concept considers the use of cylindrical concrete containers: the radwaste (encapsulated in a canister and stainless steel overpack) is embedded in a hardened self-compacting concrete buffer, and for closure of the supercontainer the remaining gap is filled by casting a self-compacting mortar (filler and lid). As a consequence, this cementitious layer, surrounding the radwaste, will be exposed immediately to the heat-emitting radioactive waste and gamma radiation with dose rates up to 20 Gy/h during hardening and hydration of the cementitious matrix. In this research study, the effect of gamma radiation on the mechanical properties (e.g. compressive strength) and the microstructure of the cementitious samples is investigated thoroughly. By means of compressive strength determination and by analysing the microstructure of the cementitious samples, the effect of gamma radiation during the hardening process of the samples is identified. Small self-compacting mortar cubes were cast and irradiated immediately by gamma rays during hardening. The effect of the total absorbed dose (Gy) and the applied dose rate (Gy/h), in combination with different hardening times at first exposure and total irradiation times is determined. Furthermore, the impact of the composition of the cementitious mortar (e.g. by changing the cement type and the water-to-cement ratio (W/C-ratio)) is investigated. Throughout the test program it was found that a strength loss due to gamma irradiation can be expected, influenced by the total received dose and by the applied dose rate. Furthermore, the age at which irradiation starts (hardening time at first exposure), plays a role in the effect of the gamma irradiation. A correlation between the strength of the mortar samples and its microstructure is found by means of fluorescence microscopy on thin sections and nitrogen adsorption tests: by applying gamma radiation the capillary porosity, the pore volume distribution and the specific surface of the pores is affected. Scanning electron microscopy (SEM) also revealed a change in microstructure due to gamma radiation. Keywords Supercontainer; Gamma radiation; Self-compacting mortar; Strength; Microstructure
E-info
https://repository.uantwerpen.be/docman/iruaauth/455df3/f989867.pdf
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000358468300023&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000358468300023&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle