Completely recyclable concrete : how does the cement paste behave during reclinkering?

It is known that the concrete industry has a big impact on the environment: large amounts of natural resources are used for aggregate and cement production, the cement manufacturing process is energy intensive and is responsible for 5U+20138% of the global anthropogenic carbon dioxide emissions. Last but not least, the construction sector is an important producer of waste. For this reason the concept of Completely Recyclable Concrete (CRC) has been developed. After the demolition of a CRC construction, the material cycle is closed as the concrete rubble is given a second life as raw material for cement production, without need for ingredient adjustments. Therefore, the concrete mixture is designed to be chemically equivalent to the raw material for cement production. Of course, cement is an important ingredient within CRC and in this study, it is investigated how the hydrated cement paste behaves during reclinkering. Therefore, the reactions occurring during heating and reclinkering of a hydrated cement paste and of a CRC sample were investigated and compared. A hydrated cement paste and a hydrated CRC sample were ground in a planetary ball mill. Samples were fired at predefined temperatures up to 1450°C and quenched in order to study the clinker or pre-clinker phase assemblage. A series of X-ray diffraction (XRD) analyses were then performed on the obtained clinkers. Microscopic analyses were used to visualize the different clinker minerals with a water and nital etch.

ISBN:9780415899529

Publication year:2012

Accessibility:Closed