Long-term irradiation effects in cementitious systems

Author(s):  
Andrey Varlakov ◽  
Alexander Zherebtsov ◽  
Michael I. Ojovan ◽  
Vladimir Petrov
2020 ◽  
Vol 4 (1) ◽  
pp. 75
Author(s):  
C. S. Paglia ◽  
A. Krattiger

The dimensional stability and durability of Acrylamide- and Methacrylate-based acrylic resins have been studied. The dimensional stability was characterized by measuring the volume expansion of samples immersed in water for a period up to 240 days or by exposing the samples to 23oC and 50 per cent, 90 per cent relative humidity and by monitoring the shrinkage. The durability was investigated by exposing the resins to cyclic variations of temperature in air and in water. The resins generally exhibit a significant volume change up to 160 per cent of the initial volume when immersed in water or exposed to a relatively dry atmosphere (23oC and 50 per cent). A general increase in the material stiffness and/or crack formation on the surface of the resin is observed. On a long-term basis, the durability of the resins may significantly vary with occasionally a partial or complete deterioration of the some resins. A general better dimensional stability and durability is observed for the Methacrylate-based resins as compared to the Acrylamide-based resins.


Author(s):  
Zoran Drace ◽  
Michael I. Ojovan

The IAEA Coordinated Research Project (CRP) on cementitious materials for radioactive waste management was launched in 2007 [1, 2]. The objective of CRP was to investigate the behaviour and performance of cementitious materials used in radioactive waste management system with various purposes and included waste packages, wasteforms and backfills as well as investigation of interactions and interdependencies of these individual elements during long term storage and disposal. The specific research topics considered were: (i) cementitious materials for radioactive waste packaging: including radioactive waste immobilization into a solid waste form, (ii) waste backfilling and containers; (iii) emerging and alternative cementitious systems; (iv) physical-chemical processes occurring during the hydration and ageing of cement matrices and their influence on the cement matrix quality; (v) methods of production of cementitious materials for: immobilization into wasteform, backfills and containers; (vi) conditions envisaged in the disposal environment for packages (physical and chemical conditions, temperature variations, groundwater, radiation fields); (vii) testing and nondestructive monitoring techniques for quality assurance of cementitious materials; (viii) waste acceptance criteria for waste packages, waste forms and backfills; transport, long term storage and disposal requirements; and finally (ix) modelling or simulation of long term behaviours of cementations materials used for packaging, waste immobilization and backfilling, especially in the post-closure phase. The CRP has gathered overall 26 research organizations from 22 Member States aiming to share their research and practices on the use of cementitious materials [2]. The main research outcomes of the CRP were summarized in a summary report currently under preparation to be published by IAEA. The generic topical sections covered by report are: a) conventional cementitious systems; b) novel cementitious materials and technologies; c) testing and waste acceptance criteria; and d) modelling long term behaviour. These themes as well as all contributions of participating organizations were further developed in the individual reports to be presented in the IAEA publication. The CRP facilitated the exchange of information and research co-operation in resolving similar problems between different institutions and contributed towards improving waste management practices, their efficiency and general enhancement of safety.


Author(s):  
Aline de Souza Oliveira ◽  
Romildo Dias Toledo Filho ◽  
Eduardo de Moraes Rego Fairbairn ◽  
Luiz Fernando Cappa de Oliveira ◽  
Otávio da Fonseca Martins Gomes

2016 ◽  
Vol 63 ◽  
pp. 132-135
Author(s):  
Tomo Harata ◽  
Masami Aono ◽  
Hisashi Miyazaki ◽  
Nobuaki Kitazawa ◽  
Yoshihisa Watanabe

2020 ◽  
Vol 10 (2) ◽  
pp. 147-164
Author(s):  
Radhakrishna G. Pillai ◽  
Ravindra Gettu ◽  
Manu Santhanam

About a decade of research carried out at IIT Madras on cementitious systems has shown that the partial replacement of portland cement with supplementary cementitious materials (SCMs) has benefits as well as limitations. The SCMs do not adversely affect the long-term compressive strength and drying shrinkage of concretes, though there may be some compromise in workability and the resistance against plastic shrinkage cracking. Through the assessment of the chloride ingress rate in concrete and chloride threshold of steel, it is evident that the use of SCMs could significantly enhance the service life under chloride attack, though there is a reduction of the carbonation resistance. More importantly, SCMs can lead to significant reduction of the carbon footprint of concrete, and hence, are essential to achieve sustainability.


1997 ◽  
Vol 506 ◽  
Author(s):  
V.A. Sinitsyn ◽  
D.A. Kulik ◽  
M.S. Khodorivsky ◽  
I.K. Karpov

ABSTRACTConcrete and other cement-based materials are increasingly utilized as major structural components of the disposal facilities for low-level and intermediate-level radioactive waste (LLW/ILW). At the same time. cementitious materials function as engineered barriers against migration of radionuclides and other hazardous compounds [1]. Taking into account the expected operation times of such constructions, the long-term prediction of environmental interactions and stability of concretes is important for the development of reliable facilities for LLW/ILW disposal. Thermodynamic approach has been widely used to promote understanding of chemical phenomena in cementitious systems. Recently, several authors attempted to demonstrate usefulness of computer codes for description of the available experimental data and prediction of cement/water equilibria [1-5]. These calculations were based on the Law-of-Mass Action - Reaction Stoichiometry Algorithm (LMA-RSA), widely applied so far in speciation modeling [6]


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