Low Temperature Belite Binder – A Durable Alternative For Ordinary Portland Cement?
Bettina Kraft, Matthias Müller, Sophie Unbehau, Horst‐Michael LudwigAbstract
A promising alternative to Ordinary Portland cement is low‐temperature belite binder (LTBB), part of the C‐S‐H binder family. It is produced in two steps: first, hydrothermal synthesis of α‐dicalcium silicate hydrate (α‐C 2 SH), followed by thermal activation below 500 °C. The resulting binder consists of highly reactive belite polymorphs, inert γ‐C 2 S, and a reactive amorphous phase. Hydration studies show that LTBB behaves similarly to C 3 S, but due to its low C/S ratio, it forms only small amounts of Ca(OH) 2 . Its pore structure is mainly capillary, leading to limited chloride and frost resistance. However, it shows good potential to mitigate alkali–silica reaction and strong resistance to salt frost attack when air voids are properly introduced. Despite its low Ca(OH) 2 content, LTBB has high carbonation resistance. This is attributed to γ‐C 2 S carbonation, which densifies the structure and can also improve resistance to chloride ingress. LTBB also exhibits rapid strength development, reaching about 75% of its 28‐day strength after two days. Combining LTBB with GGBFS further enhances workability, strength, and chloride resistance.