Assessment of the Efficiency of Mechanical Grinding and Calcination Processes for Construction and Demolition Waste as Binder Replacement in Cement Pastes: Mechanical Properties Evaluation

Reducing carbon dioxide emissions is a key priority in the European Union, which aims to achieve carbon neutrality by 2050. Construction has a key role to play in this effort, as it is responsible for a significant proportion of greenhouse gas emissions, especially due to cement production. At the same time, waste reuse emerges as a key strategy within the circular economy, another pillar of European policies. By valuing byproducts and waste, such as construction and demolition waste (CDW), it is possible to reduce the extraction of natural resources, amount of waste sent to landfills, and emissions associated with the production of new materials. This study, with the main objective of evaluating the possibility of using CDW as supplementary cementitious materials, emerges as a possible solution to reduce these problems. Two CDW treatment methods were used: (i) mechanical grinding and (ii) calcination. The mechanical grinding method, even with the use of laboratory equipment, has shown that it is possible to obtain CDW particles with characteristics suitable for replacing cement. For the calcination process, temperatures between 600 °C and 800 °C were the most suitable. The results proved that the replacement of cement by CDW in pastes resulted in suitable behavior for the construction industry, having revealed an incorporation content of up to 25% CDW, a compressive strength and strength activity index higher than that found for pastes developed with fly ash. Regarding the calcination process, this revealed an improvement in the compressive strength of the developed pastes, resulting in an increase in strength activity index of between 7 and 10%.