ISSN:
1435-1536
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Description / Table of Contents:
Zusammenfassung Der Hydratationsprozeß von Zement, Ca3SiO5 und Ca2SiO4 wurde dielektrisch zusätzlich durch Messungen der elektrischen Leitfähigkeit untersucht. Die Hochfrequenzverluste von Ca3SiO5 sind in den ersten Stadien der Hydratation groß und nehmen mit Alterung ab. Dagegen wächst tgδ für Ca2SiO4 zunächst und durchläuft ein breites Maximum bis etwa 300 Stunden. In einer Zementpaste verhält sich die tgδ-Kurve ähnlich wie bei Ca3SiO5, zeigt jedoch einen kleinen und diffusen Pik zwischen 200 und 300 Stunden. Die Ergebnisse werden gemeinsam mit der dielektrischen Leitfähigkeit diskutiert.
Notes:
Summary The results obtained from the dielectric measurements on the hydration process of cement paste are summarized as follows. 1. In the high frequency loss measurement, the tanδ of Ca3SiO5 showed a large value in the beginning and then decreased gradually with the curing age. It seems to be due to the decrease of the ions which contributes to the electric conductivity by the micelle formation and the fixation of ions with the progress of the hydration. 2. In Ca2SiO4, the tanδ increases with the increase in the curing age and then decreases gradually after passing through the broad peak. Compared with the electric conductivity curve at low frequency, it is considered that not only the loss (σ term) due to the electric conductivity but also the loss (ε″ term) due to the dielectric polarization of the quasi-structural group such as the ionic micelle formation and the ion adsorbed layer contribute to the high frequency loss of Ca2SiO4. 3. In cement paste, the tanδ appears to be the sum of the tanδ of Ca2SiO4 and Ca3SiO5. In this case, the setting time of cement paste comes about on the tanδ curve. 4. The results obtained by the electric conductivity measurements seem to support the above conclusion. 5. The results obtained in the present study showed the similar tendency to those obtained in the previous nuclear magnetic resonance study.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01500290
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