Search results
Results from the WOW.Com Content Network
Ettringite is a hydrous calcium aluminium sulfate mineral with formula: Ca 6 Al 2 (SO 4) 3 (OH) 12 ·26H 2 O.It is a colorless to yellow mineral crystallizing in the trigonal system.The prismatic crystals are typically colorless, turning white on partial dehydration.
Chondrite meteorite with calcium–aluminium-rich inclusions seen as white specks. A calcium–aluminium-rich inclusion or Ca–Al-rich inclusion (CAI) is a submillimeter- to centimeter-sized light-colored calcium- and aluminium-rich inclusion found in carbonaceous chondrite meteorites.
3 A) with calcium sulfate, both present in Portland cement. [15] C 3 A + 3 CaSO 4 + 32 H 2 O → ettringite. Ettringite, the most prominent representative of AFt phases or (Al 2 O 3 − Fe 2 O 3 − tri), can also be directly synthesized in aqueous solution by reacting stoichiometric amounts of calcium oxide, aluminium oxide, and sulfate.
Calcium aluminates phase diagram Crystal structure of dodecacalcium hepta-aluminate, 12CaO·7Al 2 O 3 (C 12 A 7). [1] Calcium aluminates are a range of materials [2] obtained by heating calcium oxide and aluminium oxide together at high temperatures. They are encountered in the manufacture of refractories and cements.
Particles of refractory material in contact with aluminium can detach and become inclusions. We can find graphite inclusions (C), alumina inclusions (alpha-Al 2 O 3), CaO, SiO 2, … After some time, graphite refractory in contact with aluminium will react to create aluminum carbides (harder and more detrimental inclusions).
So, CAC cement must not be confused with calcium sulfo-aluminate (CSA) cement containing calcium sulfate and invented later in 1936. [6] The main constituent, and also the most reactive phase, of calcium aluminate cements is the monocalcium aluminate (CaAl 2 O 4 = CaO · Al 2 O 3, also written as CA in the cement chemist notation).
Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO 4 and related hydrates. In the form of γ- anhydrite (the anhydrous form), it is used as a desiccant . One particular hydrate is better known as plaster of Paris , and another occurs naturally as the mineral gypsum .
Tricalcium aluminate Ca 3 Al 2 O 6, often formulated as 3CaO·Al 2 O 3 to highlight the proportions of the oxides from which it is made, is the most basic of the calcium aluminates. It does not occur in nature, but is an important mineral phase in Portland cement .