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- Titel:
Influence of lithium carbonate and sodium polyphosphate on CA2 hydration
- Dokumenttyp:
- Konferenzbeitrag
- Art des Konferenzbeitrags:
- Poster
- Autor(en):
- Machner, Alisa; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde
- Abstract:
- Grossite (CA2) is the second main phase of alumina rich calcium aluminate cements (CAC). It is generally described as weakly reactive and therefore was of less interest for more research in the last years. New investigations could show that CA2 may play an important role during hydration at high w/s ratios [1]. Li2CO3 is already known as an accelerator for the hydration of Monocalciumaluminate (CA) [2]. Natriumpolyphosphates are known to be used for plasticizing CAC containing mixes and have a retarding influence on the hydration of CA [3]. For investigation of CA2 hydration in addition with the two additives mixtures of 50 wt. - % of synthesized CA2 and 50 wt.-% filler were used. Li2CO3 was added to the mixing water in concentrations of 0.01, 0.05, 0.1 and 0.5 wt.-% with respect to the dry mix. The influence of Natriumpolyphosphate on hydration of CA2 was investigated for of 0.01 and 0.1 wt.-% with respect to the dry mix. Also a reference mixture without additives, only containing CA2 and filler, was investigated. Heatflow calorimetry for 45 hours und a qualitative X-ray diffraction analysis of the hydrated cement mixes after three days of hydration were performed. The results of heatflow calorimetry and qualitative X-ray diffraction confirmed hydration of the CA2 in the mixtures. An acceleration of the CA2 hydration could clearly be shown for the additions of lithium carbonate (Li2CO3). Nevertheless, the effect is by far not as intense as observed for CA hydration. The cumulated heat of hydration after 45 hours (H45-value) with the different concentrations of Li2CO3 did not show differences. A retarding influence of the plasticizer natriumpolyphosphate could also be shown on hydration of CA2. But with the addition of 0.1 wt.-% natriumpolyphosphate the hydration of CA2 was strongly retarded and could not be observed anymore within 45 hours. For the addition of 0.01 and 0.1 w.-% natriumpolyphosphate the conclusion could be drawn that higher concentrations have a very strong influence on the kinetics of the hydration reaction of CA2. Literature: [1] Klaus, S.; Neubauer, J. & Goetz-Neunhoeffer, F., Cement and Concrete Research, 2013, 43/, 62-69, [2] Willmes, A. (2007), Verlag Harri Deutsch, Frankfurt a. M., [3] Nilles, V., Plank, J. (2012), Cement and Concrete Research 42: 736-744.
- Herausgeber:
- Gesellschaft Deutsche Chemiker e.V. (GdCh)
- Kongress- / Buchtitel:
- 1st International Conference on the Chemistry of Construction Materials (ICCCM)
- Ausrichter der Konferenz:
- Gesellschaft Deutsche Chemiker e.V. (GdCh) - Fachgruppe Bauchemie
- Datum der Konferenz:
- 06.-08.10.2013
- Verlagsort:
- Berlin
- Jahr:
- 2013
- Reviewed:
- nein
- Sprache:
- en
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