Influence of calcium to silica ratio on aluminium uptake in calcium silicate hydrate

A strong correlation between the aqueous aluminium concentration and the aluminium uptake in the solid phase is observed. At high Ca/Si ratios, aluminium in C-S-H is observed mainly as octahedrally coordinated Al(VI) in TAH and the aluminium uptake increases with the aqueous aluminium concentration. At low Ca/Si ratio (≤ 0.8), aluminium is observed mainly as tetrahedrally coordinated Al(IV) and low aqueous aluminium concentrations (below detection limit) indicate a high affinity of aluminium towards C-S-H.