Background Over 90% of the power supply in Estonia comes from oil shale–fired thermal power plants. Every year some 11 million tonnes of oil shale is burned, producing more than six million tonnes of oil shale ash (OSA). Currently this is mostly disposed of by spreading on land, which causes pollution of millions of cubic metres of rainwater each year. OSA can be used as a raw material in the construction industry, and could become an interesting and cost-effective replacement for cement and other expensive additives. In Estonia, this could offset the need to import up to 500 million tonnes of natural aggregates from non-renewable sources, usually involving heavy long-distance transport across Europe. Objectives The objective of the project is to show that it is possible to convert oil shale ash (OSA) into a material that can be used in the construction sector. Specific objectives of the project include: 1) To demonstrate the technical, environmental and economic feasibility of producing aggregates and additives from OSA that have applications in the construction sector; 2) To disseminate the results of the project to target groups such as municipalities, road managers, contractors, politicians, legislative authorities, scientists and other professionals and specialists in Europe as well as in Estonia; 3) To demonstrate the environmental benefits of materials and applications based on OSA using life-cycle assessments; 4) To demonstrate the economic benefits for European companies of using OSA as an additive in certain civil engineering applications. Expected results: Given that the production of cement generates close to 0.7 tonnes of CO2/tonne of cement, it is estimated that the use of OSA could help to reduce CO2 emissions by at least 4.2 million tonnes/yr; Based on rough estimates, the costs of construction in Europe could be reduced by close to €4 billion/yr; The project will provide know-how, information, and guidance on the environmental and economic benefits, and the technical potential of using OSA in civil-engineering applications; The project will produce three practical civil-engineering applications of OSA and verify the feasibility of using OSA as a construction material, based on environmental, technical and economic criteria.