Cradle-to-grave environmental and economic sustainability of lime-based plasters manufactured with upcycled materials

The production of CaO for lime-based plaster and render generates 1.2 t CO2/t CaO, consumes 1.78 t CaCO3/t CaO. This research paper examines the environmental and economic performance of upcycling paper mill sludge (PMS) and carbide lime (CL) as replacements for hydrated lime (HL) in lime-based plasters production. For this, a new Cradle-to-Gate industrial-scale inventory is designed, upscaling recent lab-scale innovations, investigating PMS and CL treatment processes, followed by a Cradle-to-Grave scenario analysis. The results show that incorporating CL in the plaster yields better environmental and economic outcomes compared to PMS. The intermediate treatment for CL is cost-effective and has low carbon emissions. The upcycling of CL eliminates 100% of CO2 emissions, while PMS reduces emissions by 11%. The production of the traditional binder HL is more expensive than upcycling PMS (+69%) and CL (+65%), with carbon taxes accounting for 35%, 44% and 15% of production costs, respectively. The effect of an equilibrated carbon price to ensure fair market competition, considering the natural carbonation of lime (carbon credit) is discussed, and the cost assessment reveals a 47% and 54% reduction for upcycled plasters using PMS and CL, respectively, compared to traditional HL.