Economic Assessment of Post-demolition Autoclaved Aerated Concrete (AAC) Recycling and Subsequent Belite Cement Clinker Production

Autoclaved aerated concrete (AAC) is a building material with high thermal insulation properties used as masonry units in the construction of residential buildings. Although volumesof post-demolition AAC (pd-AAC) volumes are increasing, it is mainly landfilled today while landfill fees rise, legal framework conditions in Europe are tightening, and climate protection needs extensive efforts in the area of recycling. This study presents an economic assessment of pd-AAC recycling, consisting of mechanical processing (crushing, grading, purifying) and subsequent belite cement clinker production from the fine
pd-AAC fraction. The processes are modelled in detail to determine needed equipment, material flows, and energy demands for five different plant capacity scenarios. Calculated total costs of pd-AAC recycling, consisting of variable costs, fixed costs, overhead costs, and general expenses, vary significantly between the different scenarios. Today, mechanical processing of pd-AAC has total costs between 30 €/t input (plant capacity: 250,000 t/a) and around 209 €/t input (plant capacity: 10,000 t/a). The mechanical processing is
economically viable compared to regionally varying pd-AAC landfilling costs of 65–180 €/t for recycling plants with capacities of at least 25,000 t/a. ... mehrAdditional costs for subsequent belite cement clinker production from pd-AAC sum up to 800 €/t input (plant capacity: 250,000 t/a), respectively 1250 €/t input (plant capacity: 10,000 t/a). Thus, the minimum sales price for the resulting belite cement clinker would need to be around 430 €/t to compete with current landfilling costs.