Closing the loop – 100% circular concrete
A technique for recovering the sand, the gravel and the cement from concrete
Concrete is the most commonly used building material all over the world. In the production process of concrete, cement is needed. During the high-energy treatment process to make cement, large quantities of CO2 are released in the atmosphere. In total, 1kg CO2 is released to make 1 kg of cement. In 2017, the cement industry alone produced 5,000 million tonnes of cement in 2017 and – as a by-product – also 5,000 million tonnes of CO2. Concrete recycling technologies will enable the concrete chain to be circular and will mitigate climate change.
It is not widely known that in the making of concrete, only the outer area of a cement particle is reached by the water. The inner part is ‘protected’ by the part that has been activated. As a result, only about 50% of the cement in concrete is ‘activated’ by the water – and in concrete and concrete waste, still half of the unused cement is present.
In traditional crushing methods, only a small amount of cement stone will be released, which is polluted with fine silicate particles and can no longer be used for making traditional cement. These traditional crushers are very heavy-duty machines, using tremendous force and pressure as they are designed to break through everything. In breaking down the concrete rubble and drying the cement stone after that, all the still unhydrated cement is definitely lost in the process.
More information about the SmartCrusher technology here.