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Abstract
Calorimetry was applied to follow the hydration of special cement mixtures exhibiting expansion or shrinkage compensation. The standard, common cements show generally less or more visible shrinkage on setting and hardening but mixed with and expansive agent, usually of aluminate and sulfate nature, they can exhibit the increase of volume. The calcium aluminate cement CAC 40 was ground together with special sulfate–lime sinter to produce an expansive additive to Portland cement (CEM I 42.5R). The expansive additive in the environment of hydrating cement transforms into ettringite at “right time” to give expansion before the final setting and hardening takes place. In the experiments the proportions of components of expansive mixture and basic cement were variable. The rate of hydration versus time for common cements is commonly known and reflects the moderate setting and early hardening during the first days after mixing with water (two peaks and the induction period between them). The aim of measurements presented in this study was to show the course of heat evolution curve and the heat evolved values, equivalent to the acceleration/retardation of hydration, in case of the paste with the expansive mixture, as well as the pastes produced from Portland cement and the components of expansive additives added in variable proportions. It was possible to see how the calorimetric curve and consequently the hydration process itself declines from the controlled setting/hardening. These measurements were supplied by the examples of phase composition studies by XRD.
Introduction Monolithic refractory concretes with calcium aluminates cement as binding agent have been manufactured for over 80 years now. First, refractory concretes were based on high cement formulations. Today, accent is on
Introduction Calcium aluminate cements (CAC) are special hydraulic binders, especially used in refractory concretes. Castable refractories containing CAC are used in different furnaces lining applications in ceramic, cement
an expansive additive composed of calcium sulfoaluminate components or the mixture of calcium aluminate cement and calcium sulfate (gypsum or anhydrite) [ 6 , 7 ]. These additives in the environment of hydrating cement transform into ettringite—3CaO
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´ndez L Andrade C . Microstructure development in mixes of calcium aluminate cement with fume or fly ash . J Therm Anal Calorim. 2009 ; 96 ( 2 ): 335 – 45 http://dx.doi.org/10.1007/s10973
. 41. Pacewska B , Wilińska I , Nowacka M . Studies on the influence of different fly ashes and Portland cement on early hydration of calcium aluminate cement . J Therm Anal Calorim. 2011 . doi
. Hidalgo , A , Garcia , JL , Alonso , MC Fernandez Andrade , C 2009 Microstructure development in mixes of calcium aluminate cement with silica fume or fly ash . J Therm Anal Calorim 96 2 335 – 345 10.1007/s10973
Artificial pozzolanic cement pastes containing burnt clay with and without silica fume
Physicochemical, microstructural and thermal characteristics
aluminate cement with silica fume or fly ash . J Therm Anal Calorim . 2009 ; 96 : 2 335 – 345 . 10.1007/s10973-007-8439-3 . 26. Chaipanich , A , Nochaiya , T . Thermal analysis and
