The Dissolution Behavior in Alkaline Solutions of a Borosilicate Glass with and without P₂O₅

Abstract

There are a variety of applications for glasses in alkaline environments, including glass fibers and glass-coated steel to reinforce concrete structures. To understand how a simple glass reacts in such environments, the dissolution behavior of a 25Na2O-25B2O3-50SiO2 (mol%) glass, doped with and without 3 mol% P2O5, in pH 12 KOH and pH 12 KOH saturated with Ca2+ ions was studied. Ca2+ ions in the solution significantly reduce the glass dissolution rate by forming a passivating calcium silicate hydrate (C-S-H) gel layer on the glass surface. When these corroded glasses were then exposed to Ca-free KOH, the C-S-H layer redissolves into the undersaturated solution and the glass dissolution rate increases. For phosphate-doped borosilicate glass, PO4 3- units released from the dissolving glass react with Ca2+ ions in saturated solutions to form crystalline hydroxylapatite on the glass surface, but this layer does not protect the glass from corrosion as well as the C-S-H does. The nature of the C-S-H layer was characterized by Raman spectroscopy, which reveals a gel layer constituted mainly of silicate anions.

Department(s)

Materials Science and Engineering

Second Department

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Alkalinity; Calcium Silicate; Concretes; Glass; Hydrates; HydrationIons; Silicate Minerals; Steel Fibers; Alkaline Environment; Alkaline Solutions; Chemical Durability; Dissolution Behavior; Reinforce Concrete Structure; Saturated Solutions; Borosilicate Glass

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2017 Blackwell Publishing Inc., All rights reserved.

Publication Date

01 Oct 2017

Link to Full Text

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