The rapid depletion of natural resources in modern society and the high amount of generated waste have motivated research in this field towards more sustainable and alternative building materials. The negative effects on the environment and the target of more green solutions can be obtained by reducing the waste generation and also by reusing the generated waste.

Construction and demolition (C&D) waste represents approximately 25%-30% of the amount of waste produced in the European Union (EU) and is composed by various materials, namely concrete, glass, plastic, bricks, wood, asbestos, metals, solvents and excavated soil, many of which have a high resource value. In this context, C&D waste has been identified as a priority by the EU with the main goal that by 2020 a minimum of 70% of non-hazardous C&D wastes shall be reused, recycled or recovered, including as a substitute of other materials.

Furthermore, the demand for polyurethane is continually growing in EU. More than 3.5 million tonnes of this insulation material are used each year and approximately 70% is presented in the form of foam. It is also estimated that about 20% of it ends up as waste and a vast majority is taken to landfill, corresponding to about 460 000 tonnes per year.

In order to achieve this recovery target, EU is encouraging the circular economy principles, establishing measures to be implemented throughout the whole cycle, from design, production and consumption to waste management.

It is intended with the research work here presented to contribute to the scientific knowledge regarding the incorporation of C&D and polyurethane foam wastes in compressed blocks. Different mixtures were defined considering different percentages of polyurethane foam waste and activated with a solution based on sodium hydroxide and sodium silicate. The thermal performance assessment of compressed blocks panels with the resulting mixtures was carried out using experimental work. The influence of different percentages of polyurethane foam waste on the compressed blocks thermal behaviour was analysed. Experimental measurements also allowed to determine heat flux, inner surface temperatures and thermal transmission coefficient for different solutions of compressed blocks.