| abstract |
Improved and durable alkali resistant glass compositions are conveniently formed from economical and abundant raw materials to withstand high temperature, high alkaline environments such as curing of cementitious products in autoclaves . The glass composition contains a high concentration of calcium and iron and a relatively low concentration of alkali metals compared to other alkali-resistant glass products, and essentially has a Wt ratio of 35% or more of Si 2 O 3 , 1 to 25%. CaO, 1-15% Fe 2 O 3 , 1-10% R 2 O, and an amount of Al 2 O 3 such that the ratio of SiO 2 : Al 2 O 3 is greater than 1. Alkali resistance is improved by forming a passive layer on the surface of a glass product by treating the product hydrothermally in a basic environment. In order to further improve the alkali resistance, zirconia and / or titania may be added to the composition. |