[en] Radioactive waste with widely varying characteristics is generated from the operation and maintenance of nuclear power plants, nuclear fuel cycle facilities, research laboratories and medical facilities. This waste must be treated and conditioned, as necessary, to provide waste forms acceptable for safe storage and disposal. Many countries use cementitious materials (concrete, mortar, etc.) as a containment matrix for immobilization, as well as for engineered structures of disposal facilities. Radionuclide release is dependent on the physicochemical properties of the waste forms and packages, and on environmental conditions. In the use of cement, the diffusion process and metallic corrosion can induce radionuclide release. The advantage of cementitious materials is the added stability and mechanical support during storage and disposal of waste. Long interim storage is becoming an important issue in countries where it is difficult to implement low level waste and intermediate level waste disposal facilities, and in countries where cement is used in the packaging of waste that is not suitable for shallow land disposal. This coordinated research project (CRP), involving 24 research organizations from 21 Member States, investigated the behaviour and performance of cementitious materials used in an overall waste conditioning system based on the use of cement - including waste packaging (containers), waste immobilization (waste form) and waste backfilling - during long term storage and disposal. It also considered the interactions and interdependencies of these individual elements (containers, waste, form, backfill) to understand the processes that may result in degradation of their physical and chemical properties. The main research outcomes of the CRP are summarized in this report under four topical sections: (i) conventional cementitious systems; (ii) novel cementitious materials and technologies; (iii) testing and waste acceptance criteria; and (iv) modelling long term behaviour. The individual contributions of participating organizations and the overall conclusions of the CRP are also included. CRP participants shared research and practices on the use of cementitious materials. Such exchange of information and cooperation in resolving common problems between different institutions in Member States contributes to improving waste management practices, including their efficiency and safety. The CRP promoted the exchange of information on ongoing research and development activities, and facilitated access to the practical results of the application of advanced waste management practices for the conditioning of specific types of waste. As a result of the CRP, new knowledge and practical experience will be transferred to Member States to improve their radioactive waste management practices. This publication can serve as a screening tool to identify cementitious systems and technologies to meet specific waste management objectives in terms of the waste generated, the technical complexity of waste streams, the available economic resources, the environmental impact considerations and the desired end product (waste form). It can be used to compare cementitious systems and technologies in order to reach an informed decision based on safety, technological maturity, economics and other local needs