CO2-curing of carbon-reducing slag-based masonry bricks at elevated pressures in pre-industrial scale

Abstract

The production of masonry bricks consumes enormous amounts of resources and causes high CO2 emissions. Most of the CO2 emissions are due to the use of hydraulic binders. We substitute conventional binders by different slag types that are a secondary-product of the steel industry to produce masonry bricks and perform CO2-curing. The scale-up from laboratory to pre-industrial scale including a lifecycle assessment (LCA) is focused. Literature values of the global warming potential (GWP) of sand-lime bricks serve as reference for the LCA. All slag-based CO2-cured bricks reach compressive strengths (24 to −49 MPa) higher than those of sand-lime bricks (12 to −20 MPa). The optimal curing parameters are 15 bar, 50 °C and 6 h. For these process conditions, autoclaves of the sand-lime brick industry can be modified for the usage of CO2. The LCA shows a CO2-saving potential of 337 kgCO2,eq/m3brick by carbonation process, compared to the conventional sand-lime bricks. CO2-curing of slag-based bricks has great potential for industrial implementation.