John F. MacDowell

Stratlingite and Hydrogarnet from Calcium Aluminosilicate Glass Cements

Calcium aluminosilicate glass cements that hydrate directly to stratlingite (2CaO·Al 2 O 3 SiO 2 · 8H 2 O) and/or hydrogamet solid solution (3CaO·Al 2 O 3 ·XsiO 2 ·[16–2X]H 2 O) are described. Hydrogamet develops rapidly during curing of pastes containing between 12 and 16 wt.% SiO 2 , while stratlingite grows more slowly in bladed radial spherulites in compositions containing 18 to 25% SiO 2 Compressive strengths between 35 and 70 MPa, 20–35% porosity, and excellent thermal and chemical stability are characteristic of the cured hydrogamet cements, while the stratlingite pastes have strengths between 70 and 140 MPa and 1–10% porosity. A preferred composition area is described that yields mixtures of the two hydrated phases, resulting in a useful combination of low porosity and high early strength.