All traditional crushing installations originate from mining techniques. They are crushing tools developed to, for example, reduce the size of coal or metal ore. The use of these machines on concrete rubble is the same: large pieces of concrete (structural parts, concrete paving stones, etc.) are reduced to small pieces of concrete (recycled concrete aggregates). With traditional breaking, about 45% of the original concrete rubble will be released as 0 - 4 mm recycled sand. To date, there is no serious application for this material.
In contrast to traditional crushers, Slimbreker does not break through the sand and gravel but only breaks the cement hydrate (the cement stone, the reaction product of cement with water), the glue that holds the sand and gravel together. The breaking of the cement hydrate is done by applying transverse and frictional forces. Due to the operating principle, the forces necessary for a smart breaker are approximately 10% of those using conventional breaking.
Microwave fragmentation and microwave dehydration of concrete
Aggregates and cement phases exhibit different thermal properties, which is favorable for the formation of cracks and fractures along the phase boundaries and separation during rapid heating. After all, the difference in thermal expansion of the aggregates and cement phases is quite large (50-300%). The use of microwaves creates internal tension in the concrete mass which leads to the formation of cracks and breaks along the phase boundaries.
In addition, the heating of (bound and unbound) water also creates internal pressure which promotes fragmentation. Dehydrating the cement and thereby removing its binding properties, also contributes to a thorough separation of concrete into its constituent components.