Influence of amorphous silica on the hydration of tricalcium aluminate

Amorphous silica influences tricalcium aluminate (3CaO.Al2O3) hydration both in pastes and in suspensions. Two heat peaks are found by isothermal calorimetry during the paste hydration of 3CaO.Al2O3. The addn. of amorphous silica causes the second heat peak to shift towards shorter reaction times and become more pronounced. In suspensions, the change in ion concn. in the water phase is not influenced by the presence of amorphous silica except that the change in concn. occurs more quickly. Quant. x-ray anal. shows that more 3CaO.Al2O3.6H2O is present in suspensions contg. amorphous silica than in silica-free suspensions at equal hydration times. [on SciFinder (R)]