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Open AccessArticle

Reactivation of a Retarded Suspension of Ground Granulated Blast-Furnace Slag

Building Material and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany
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Academic Editor: Jorge de Brito
Materials 2016, 9(3), 174; https://doi.org/10.3390/ma9030174
Received: 25 November 2015 / Revised: 19 February 2016 / Accepted: 1 March 2016 / Published: 7 March 2016
(This article belongs to the Section Advanced Composites)
An effective retarded suspension of ground granulated blast-furnace slag (GGBFS) needs a strong activator to reactivate the hydration. In this research study, sodium hydroxide (NaOH) as an alkali activator in two different concentrations (30 and 50 wt.%) was used to overcome the retardation and give the hardened GGBFS the reasonable strength. The study was carried out with a mixture of GGBFS, a solution of 1.0 wt.% d-gluconic acid (C6H12O7) as a retarder in the mixing water and a methyl cellulose as a stabilizer. The reactivation was executed after seven different periods (up to 28 days) after the system was retarded. The following investigations were performed: slump test, measurement of ultrasonic (US) velocity, compressive strength and gross density, thermogravimetry (TG) and scanning electron microscopy (SEM). The analyses of the hardened samples were carried out seven, 28 and 90 days after the reactivation. The result of the study is an effective reactivation of a retarded suspension. In this case, the activator with 50 wt.% NaOH shows a very high performance. The setting time of the reactivated binders is much longer compared to the reference, but, in the longer term, the compressive strength and the progress of the hydration exceed the performance of the reference. View Full-Text
Keywords: retardation; reactivation; ground granulated blast-furnace slag; d-gluconic acid; NaOH; hydration study retardation; reactivation; ground granulated blast-furnace slag; d-gluconic acid; NaOH; hydration study
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MDPI and ACS Style

Schneider, N.; Stephan, D. Reactivation of a Retarded Suspension of Ground Granulated Blast-Furnace Slag. Materials 2016, 9, 174.

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