Assessment of the efficiency of mechanical grinding and calcination processes for construction and demolition waste as binder replacement in cement pastes: mechanical properties evaluation

Abstract

Reducing carbon dioxide emissions is a key priority in the European Union, which aims to achieve carbon neutrality by 2050. The constructionConstruction has a key role to play in this effort, as it is responsible for a significant proportion of greenhouse gas emissions, especially due to the cement production. At the same time, waste reuse emerges as a key strategy within the circular economy, another pillar of European pol-icies. 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 supple-mentary cementitious materials, emergeemerges 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 equip-ment, has shown that it is possible to obtain CDW particles with characteristics suita-ble 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 re-vealed up to 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. Re-garding 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%.