This study introduces the concept of Bio-LC³ in which biomass waste is upcycled into sustainable ingredients in limestone calcined clay cement (LC³) by partially replacing cement. Specifically, rice husk ash, rice husk biochar, sawdust biochar and titanium dioxide (TiO₂)-coated sawdust were chosen as the partial replacement for Ordinary Portland Cement (OPC). 

The novelty of this study lies in, firstly, a high replacement rate of 5-15 wt% was applied to replace OPC with the abovementioned biomass waste. Secondly, Accelerated Carbon Curing was applied to these different types of LC³ so that we could evaluate the effects of the different waste on carbon mineralization, strength, water absorption and thermal stability of LC³. 

It was found that it is possible to replace 15 wt% of cement with rice husk ash or 5 wt% of cement with TiO₂-coated sawdust and achieve similar compressive strength to that of carbonated LC³ control, which was in turn significantly stronger than LC³ control without carbonation. Carbonating LC³ with TiO₂-coated sawdust enhanced the reaction between mineralized carbonates (calcite) and metakaolin. In contrast, carbonation of sawdust biochar reduced calcite-metakaolin and metakaolin-Portlandite (CH) reactions, thus lowering its 28-day strength. Presence of rice husk biochar enhanced capture of carbon, as well as the overall bulk thermal stability.

All in all, these results showed that it is possible to further increase the sustainability of LC³ by valorizing different types of bio-waste and develop special functions that enhance the overall usefulness of these sustainable materials.