The negative emissions of the C-LWA are especially promising considering the high emissions and energy consumption of the traditionally-produced LWA. The latter are usually hardened by sintering at temperatures of 900-1200 °C . The production process of the sintered LWA causes emissions of about 0.05-0.06 kg CO 2 /kg . Hence, replacement of the C-LWA with sintered LWA would actually increase the emissions of concrete by about 10-12 kg CO 2 /m 3 , i.e. by about 5% (for the particular mix composition as presented in Table ). The emissions balance of the C-LWA vs sintered LWA would become even more extreme for an actual lightweight concrete (the concretes produced in this study contained a relatively small amount of LWA and were classified as normal weight concretes). For an exemplary case of a concrete with 1800 kg/m 3 density and ca. 45% volume occupied by lightweight aggregates (with density of 1000 kg/m 3 ), the emissions of the concrete with sintered LWA would reach about 230 kg CO 2 /m 3 , whereas the use of C-LWA would lead to negative emissions of concrete of about -290 kg CO 2 /m 3 . This shows the very high potential of the C-LWA as a carbonremoval technology, in particular in lightweight concrete.