Structure and mechanical properties of aluminosilicate geopolymer composites with Portland cement and its constituent minerals

Journal Article · Sat May 15 00:00:00 EDT 2010 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2009.12.003· OSTI ID:21344763

Tailby, Jonathan ^[1]; MacKenzie, Kenneth J.D. ^[1]

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1. School of Chemical and Physical Sciences Victoria University of Wellington, P.O. Box 600 Wellington (New Zealand)

The compressive strengths and structures of composites of aluminosilicate geopolymer with the synthetic cement minerals C{sub 3}S, beta-C{sub 2}S, C{sub 3}A and commercial OPC were investigated. All the composites showed lower strengths than the geopolymer and OPC paste alone. X-ray diffraction, {sup 29}Si and {sup 27}Al MAS NMR and SEM/EDS observations indicate that hydration of the cement minerals and OPC is hindered in the presence of geopolymer, even though sufficient water was present in the mix for hydration to occur. In the absence of SEM evidence for the formation of an impervious layer around the cement mineral grains, the poor strength development is suggested to be due to the retarded development of C-S-H because of the preferential removal from the system of available Si because geopolymer formation is more rapid than the hydration of the cement minerals. This possibility is supported by experiments in which the rate of geopolymer formation is retarded by the substitution of potassium for sodium, by the reduction of the alkali content of the geopolymer paste or by the addition of borate. In all these cases the strength of the OPC-geopolymer composite was increased, particularly by the combination of the borate additive with the potassium geopolymer, producing an OPC-geopolymer composite stronger than hydrated OPC paste alone.

• OSTI ID: 21344763
• Journal Information: Cement and Concrete Research, Vol. 40, Issue 5; Other Information: DOI: 10.1016/j.cemconres.2009.12.003; PII: S0008-8846(09)00349-4; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0008-8846
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORATES
COMPRESSION STRENGTH
HYDRATION
LAYERS
MICROSTRUCTURE
MINERALS
NUCLEAR MAGNETIC RESONANCE
PORTLAND CEMENT
POTASSIUM
SCANNING ELECTRON MICROSCOPY
SODIUM
WATER
X-RAY DIFFRACTION
ALKALI METALS
BORON COMPOUNDS
BUILDING MATERIALS
CEMENTS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
HYDROGEN COMPOUNDS
MAGNETIC RESONANCE
MATERIALS
MECHANICAL PROPERTIES
METALS
MICROSCOPY
OXYGEN COMPOUNDS
RESONANCE
SCATTERING
SOLVATION