The Behaviours of Cementitious Materials in Long Term Storage and Disposal: An Overview of Results of the IAEA Coordinat
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The Behaviours of Cementitious Materials in Long Term Storage and Disposal: An Overview of Results of the IAEA Coordinated Research Project Zoran Drace1 and Michael I. Ojovan 2 1 International Atomic Energy Agency, Wagramer Strasse 5, PO Box 100, 1400 Vienna, Austria 2 Immobilisation Science Laboratory, Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom ABSTRACT Cementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Both conventional and novel cementitious materials are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system. The behaviour and performance of cementitious materials including waste package components, wasteform and backfilling were analysed within the IAEA Coordinated Research Project which involved 26 research organizations from 21 Member States MS). The paper presents briefly the main research outcomes for conventional cementitious systems; novel materials and technologies; testing and waste acceptance criteria; and modelling long term behaviour.
INTRODUCTION Cement has many favourable properties, both chemical and physical, making it a desirable matrix for the encapsulation of radioactive and toxic wastes. Chemically cement has a high pH (e.g. its pore water) and forms hydration products which favour sorption and ion substitution [1]. Physically, cement forms a solid package with a low permeability in its hardened state which can withhold the waste material, allowing for safe intermediate transportation and storage. Cement is also an inexpensive and readily available material, durable, fluid when initially cast and tolerant to a variety of waste forms, including those in solid and liquid states. Cements have also been tested to show their stability when irradiated and ability to act as radiation shielding. Cementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Conventional cementitious materials such as Portland cement and composite cements with supplementary cementitious materials in the form of fly ash, iron blast furnace slag, silica fume, natural pozzolans as well as novel cement systems such as geopolymers, high alumina (calcium sulfoaluminate), MgO-based or phosphate (acidic) cements are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system.
IAEA CRP PROGRAMME ON CEMENTS The IAEA CRP on Behaviour of Cementitious Materials gathered together researchers from 21 Member States which cover a large number of topics related to use of cementitious materials (See Table I, for details see [2]). Table 1. M
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