Heat evolution in hydrated cementitious systems admixtured with different set controlling components |
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Authors: | Z Pytel |
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Institution: | (1) Faculty of Material Science and Ceramics, University of Science and Technology AGH al. Mickiewicza 30, 30-059, Cracow, Poland |
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Abstract: | Calorimetry has been used in the investigations of cementitious systems with different set controlling admixtures. The kinetics
and mechanism of hydration process was thus characterized on two different cement clinkers mixed with calcium sulphate containing
materials. These admixtures were collected as a residue in the fluidised bed combustion (FBC) of coals with simultaneous desulphurisation
process - so-called bottom ash. Apart from anhydrite/gypsum, they were composed mainly of alumina and silica containing material
of disordered structure, originating from the coal contaminations of clay character. Anhydrite/gypsum acts as set controlling
admixture. The aluminosilicate component reacts with calcium ions released to the solution from the calcium silicate clinker
minerals.
It has been found that fluidised bed combustion wastes can be successfully used as set controlling admixture. There is no
other harmful effects; those could be easily detectable by calorimetry. However the effect is dependent upon the composition
of cement clinker. At low calcium aluminate content a slight acceleration of hydration process can be easily observed, particularly
at higher amount of admixture. In the mixtures with high calcium aluminate clinker the heat evolved is slightly reduced in
the presence of admixture. The dominating role of aluminate phase in heat evolution process within the first hours of hydration
process has been thus proved.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | heat of hydration cement setting FBC wastes |
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