Phase transformation and hydration of dicalcium silicate containing stabilizers

beta -dicalcium silicate was stabilized at room temperature and synthesized from reagent grade chemicals using B2O3, K2O or SO3 as stabilizers. B2O3 a cts as the most effective stabilizer for dicalcium silicate. Phase transfor mation from beta- to gamma -dicalcium silicate depends on the start tempera ture of quenching. Hydration heat of beta -C2S shows that SO3 delayed hydra tion at an early hydration time, but higher heat liberation rate at a later hydration time than the other stabilizers. Si-29 MAS NMR analysis shows th at the hydrate of dicalcium silicate stabilized by B2O3 is polymerized more than those of dicalcium silicates stabilized by K2O and SO3. Dicalcium sil icate presents different shapes of calcium silicate hydrate according to st abilizers: dicalcium silicate stabilized by B2O3 shows crumbled foil shape and K2O needle shape of C-S-H.