The Influence of Sodium and Potassium Hydroxide on Volume Changes in Cementitious Materials

Abstract

This research investigates the influence of alkali hydroxides on unrestrained volume changes. A detailed multi-method approach is used to characterize the progress of cement hydration, autogenous and drying volume changes (i.e., shrinkage), autogenous RH decrease, compressive strength development, solid and liquid phases and the pore structure. It is noted that under autogenous conditions, alkalis magnify shrinkage; while upon external drying the extent of shrinkage is more similar. This is contrary to expectations which suggest that the reduction in the water activity and the negative pressure developed in the liquid phase, produced by alkali enrichment, should reduce shrinkage. Analysis of the autogenous RH decrease, pore solution chemistry and the mechanical properties indicates that the bulk shrinkage response is linked to multiple parameters including: (1) increased self-desiccation at early ages, (2) a reduction in the strength (and stiffness) of alkali-enriched systems and (3) liquid saturation effects.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Alkalis (D); Compressive strength; Drying (A); Humidity; Shrinkage

International Standard Serial Number (ISSN)

0008-8846

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Elsevier Ltd, All rights reserved.

Publication Date

01 Nov 2012

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