Successful paving block production using low-carbon circular cements on an industrial scale

Figure: Heidelberg Materials

Carbonated hardened cement paste (RCP): Carbon dioxide from the exhaust gas was stored in insoluble CaCO₃ (blue). The calcium required for this purpose was leached from the cement hydrates. This results in the formation of an alumina-silica gel (green) that is a highly reactive pozzolana

Figure: Heidelberg Materials

Test specimens made in the laboratory tests

Figure: Heidelberg Materials

Production at the paving block factory of Kronimus AG in Iffezheim

Figure: Heidelberg Materials

Freeze-thaw and de-icing salt resistance according to EN 1338 Annex D (left); development of the weathering in the CDF test (right)

Figure: Heidelberg Materials

Germany is already reusing 95 % of construction and demolition debris. The ReConcrete technology of Heidelberg Materials pursues a further-reaching innovative approach of purposeful carbonation of the hardened cement paste recovered, which binds the CO₂ permanently in RCP.

Germany is already reusing 95 % of the construction and demolition debris. When recycling demolished concrete, the raw materials recovered in this process are often of a lower quality than that of the initial products. These materials are primarily used in road construction, for example, as frost protection layer. However, recycling is able to do more.

By innovative techniques of processing, the demolished concrete can be decomposed to its constituents almost separated to type. It is possible to reuse all of the sand and gravel recovered in this process for the production of high-quality...