An initial study on alkali activated limestone binders

Alkaline cements were studied using limestone as the only precursor activated with solutions of sodium hydroxide and waterglass; the activator was used at concentrations of 7 and 10%Na2O using modules of Ms = 0, 1 and 1.5. The compressive strength was followed on pastes and mortars for up to 360 day...

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Bibliographic Details
Published in:Cement and concrete research 2019-06, Vol.120, p.267-278
Main Authors: Ortega-Zavala, Dulce Esmeralda, Santana-Carrillo, José Luis, Burciaga-Díaz, Oswaldo, Escalante-García, J. Ivan
Format: Article
Language:English
Subjects:
Alkali activated cement
CaCO3
Calcium silicates
Carbonates
Cements
Characterization
Compressive strength
Hydration products
Limestone
Limestone binders
Microstructure
Mortars (material)
NMR
Nuclear magnetic resonance
Pastes
Silica gel
Silicates
Silicon dioxide
Sodium hydroxide
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Summary:Alkaline cements were studied using limestone as the only precursor activated with solutions of sodium hydroxide and waterglass; the activator was used at concentrations of 7 and 10%Na2O using modules of Ms = 0, 1 and 1.5. The compressive strength was followed on pastes and mortars for up to 360 days after an initial curing at 60 °C for 24 h. A paste with 7%Na2O and Ms = 1.5 and a mortar with 10%Na2O and Ms = 1 reached strength of 15-25 MPa after 360 days; the mortars showed trends towards higher strength with time. The characterization by SEM, EDS, XRD, FTIR indicated that the microstructure consisted of a mixture of silica gel, carbonates, C-S-H, N-C-S-H and N-S-H. 29Si MAS-NMR showed the formation of calcium silicates possibly of long chains which contributed to the strength.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2019.04.002