Influence of aluminium hydroxide and lime on the hydration of tricalcium silicate

Abstract

Experiments by isothermal calorimetry, indicate that the hydration of 3CaO·SiO2 (C3S) is influenced very little by gibbsite; it is influenced by bayerite to a somewhat larger extent. In the presence of amorphous Al(OH)3 the reaction of C3S with water shows a very complicated course and gives four heat peaks. If CaO is added in addition to this Al(OH)3, the third and the fourth heat peaks are more pronounced. From qualitative d.t.a., infra‐red, electron‐microscope and X‐ray investigations, as well as from quantitative X‐ray analysis, a reaction mechanism is proposed. The quantity of C3S reacted, determined by means of quantitative X‐ray analysis, is greater during the reaction of 2·00 g C3S with 0·40 g amorphous Al(OH)3, 0·08 g CaO and 2·00 ml water, than during the reaction of 2·00 g C3S with 2·00 ml water.

Hydration of C3S in presence of CA: Mineral‐pore solution interaction

“…Besides this, it is well known that the silicate reaction is inhibited in the presence of aluminum ions. The influence of Al(OH) 4 − on the hydration of C 3 S has been investigated extensively . However, the exact mechanism how Al(OH) 4 − retards the C 3 S hydration is not yet clear.…”