Reactive belite stabilization mechanisms by boron-bearing dopants

Journal Article · Sun Apr 15 00:00:00 EDT 2012 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2012.01.006· OSTI ID:21596964

Cuesta, Ana; Losilla, Enrique R; Aranda, Miguel A.G. ^[1]; Sanz, Jesus ^[2]

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1. Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071-Malaga (Spain)
2. Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Cantoblanco, 28049 Madrid (Spain)

Belite-rich cements hold promise for reduced energy consumption and CO{sub 2} emissions, but their use is hindered by the slow hydration rates of ordinary belites. This drawback may be overcome by activation of belite by doping. Here, the doping mechanism of B and Na/B in belites is reported. For B-doping, three solid solutions have been tested: Ca{sub 2-x/2{open_square}x/2}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x}, Ca{sub 2}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x}O{sub x/2} and Ca{sub 2-x}B{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 4}){sub x}. The experimental results support the substitution of silicate groups by tetrahedral borate groups with the concomitant substitution of calcium by boron for charge compensation, Ca{sub 2-x}B{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 4}){sub x}. Otherwise, the coupled Na/B-doping of belite has also been investigated and Ca{sub 2-x}Na{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x} series is confirmed to exist for a large range of x values. Along this series, {alpha}'{sub H}-C{sub 2}S is the main phase (for x {>=} 0.10) and is single phase for x = 0.25. Finally, a new structural description for borax doping in belite has been developed for {alpha}'{sub H}-Ca{sub 1.85}Na{sub 0.15}(SiO{sub 4}){sub 0.85}(BO{sub 3}){sub 0.15}, which fits better borax activated belite cements in Rietveld mineralogical analysis.

• OSTI ID: 21596964
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 4 Vol. 42; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BORATES
BORAX
BORON
BORON COMPOUNDS
BUILDING MATERIALS
CALCIUM COMPOUNDS
CALCIUM SILICATES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CEMENTS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
DISPERSIONS
DOPED MATERIALS
ELEMENTS
EMISSION
ENERGY CONSUMPTION
HOMOGENEOUS MIXTURES
HYDRATION
MATERIALS
MIXTURES
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SEMIMETALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
SOLID SOLUTIONS
SOLUTIONS
SOLVATION
STABILIZATION
X-RAY DIFFRACTION