Improved Artificial Aggregates for Use in Green Roof Design

The development of surfaces in cities, as a result of progressive urbanization, not only reduces the natural retention capacity of the environment but also causes changes in the water balance. In urbanized areas, the amount and intensity of rainwater discharged to receivers increase, and the time of water outflow from the catchment area shortens. Low retention does not provide effective responses to the local water deficit and does not limit the effects of excess water during flood periods. Furthermore, aging drainage systems do not always have the required hydraulic efficiency in absorbing runoff after intense and heavy rainfall or snowmelt. The aim of the work was to determine the possibility of obtaining flat aggregates with a grain size of 2–16 mm from clay-silt fractions from sedimentation tanks using selected mechanical processing methods (crushing and screening in a crusher-screener system with recycling). An important issue was the examination of the physical and mechanical properties of the produced aggregates after firing, where the work required a detailed material analysis using various research techniques, such as XRD, XRF, SEM and digital microscopy. The obtained results will allow for further research on developing the concept of technology for the production of lightweight aggregates used, for example, on building roofs. Particular attention was paid to the flat shape of the aggregate, which affects a number of its properties. To obtain a flat-shaped aggregate, the authors used a patented sieving method. The obtained materials had high cavernosity of 69% on average, water absorption of 40.7% and low bulk density of 0.82 g/cm 3 .