Acceleration of Portland cement with lithium, sodium and potassium silicates and hydroxides

These systematic investigations focus on the effect of lithium, sodium and potassium silicates (water glasses) and their hydroxides on the hydration of ordinary Portland cement. All tests were performed with CEM I 52.5 R and the different alkaline species. Besides the well examined sodium and potass...

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Bibliographic Details
Published in:Materials chemistry and physics 2020-03, Vol.243, p.122608, Article 122608
Main Author: Witzleben, Steffen Thomas
Format: Article
Language:English
Subjects:
Acceleration
Calorimetry
Cement hydration
Heat of hydration
Hydroxides
Lithium
Portland cement
Portland cements
Potassium
Potassium silicates
Silica
Silicates
Sodium
Tricalcium silicate
Ultrasonic studies
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Summary:These systematic investigations focus on the effect of lithium, sodium and potassium silicates (water glasses) and their hydroxides on the hydration of ordinary Portland cement. All tests were performed with CEM I 52.5 R and the different alkaline species. Besides the well examined sodium and potassium silicates, lithium water glasses and hydroxides were admixed. Their effects on setting time, strength, heat of hydration and phase formation of cementitious systems were compared to each other and related to the different silicate modules of the used silicates. Due to the systematic approach the investigations exhibit a new view of the reactivity of lithium, sodium and potassium in Portland cement hydration. The setting of limes was monitored by time of ultrasonic transmission. Accelerating effects of the different silicates are related to the alkaline species with comparable silicate content. The acceleration effect in the first two days could be observed trough the C3S and C–S–H content during hydration compared to the unmodified Portland cement. Resulting strength of the admixed systems are measured based on EN 196–1. [Display omitted] •Addition of up to 1% of Li-silicate to Portland cement increase setting and early flexural and compressive strength.•Addition of 1% Na- or K-silicate exhibit a slight retardation.•Addition of 2 to 10% of Li-, Na-, K-silicate expose a remarkable acceleration but a decrease in compressive strength.•Effects of the alkali ions fits to the lyotropic series of ions on macro molecules.
ISSN:0254-0584
1879-3312
DOI:10.1016/j.matchemphys.2019.122608