Interaction between alpha-calcium sulfate hemihydrate and superplasticizer from the point of adsorption characteristics, hydration and hardening process

Journal Article · Mon Feb 15 00:00:00 EST 2010 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2009.08.027· OSTI ID:21344744

Baohong, Guan; Qingqing, Ye; Jiali, Zhang; Wenbin, Lou ^[1]

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1. Department of Environmental Engineering, Zhejiang University, Hangzhou 310027 (China)

Superplasticizers (SPs), namely sulfonated melamine formaldehyde (SMF) and polycarboxylate (PC), were independently admixed with alpha-calcium sulfate hemihydrate based plaster to improve the material's performance. SMF and PC gave, respectively, 38% and 25% increases in the 2 h bending strength at the optimum dosages of 0.5 wt.% and 0.3 wt.%, which are determined essentially by the maximum water-reducing efficiency. The peak shift of binding energy of Ca2p{sub 3/2} detected by X-ray photoelectron spectroscopy (XPS) suggests that SPs are chemically adsorbed on gypsum surface. A careful examination of the strength development of set plaster allowed the hydration and hardening process to be divided roughly into five stages. SMF accelerates early hydration, while PC decelerates it. Both SPs allowed similar maximum water reductions, giving a more compact structure and a decrease in total pore volume and average pore diameter, and thus leading to higher strengths in the hardened plasters with SPs.

• OSTI ID: 21344744
• Journal Information: Cement and Concrete Research, Vol. 40, Issue 2; Other Information: DOI: 10.1016/j.cemconres.2009.08.027; PII: S0008-8846(09)00239-7; 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
ADSORPTION
BINDING ENERGY
CALCIUM SULFATES
EFFICIENCY
FLEXURAL STRENGTH
FORMALDEHYDE
GYPSUM
HARDENING
HYDRATION
MELAMINE
PERFORMANCE
PLASTICIZERS
SURFACES
WATER
X-RAY PHOTOELECTRON SPECTROSCOPY
ALDEHYDES
ALKALINE EARTH METAL COMPOUNDS
AMINES
AZINES
CALCIUM COMPOUNDS
ELECTRON SPECTROSCOPY
ENERGY
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
MINERALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
SOLVATION
SORPTION
SPECTROSCOPY
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
TRIAZINES