The Effect of Coal Ash on Synthesis and Properties of Tricalcium Silicate
Keywords:tricalcium silicate, alite, belite, coal ash, compressive strength, calcium silicate hydrate, portlandite.
The aim of the research is to investigate the effect of coal ash on tricalcium silicate synthesis and properties of synthesis
products. Tricalcium silicate was obtained as a result of the synthesis of limestone (CaCO3) and amorphous SiO2⋅nH2O
stoichiometric mixture. The synthesis was carried out by burning the mixture treble at 1500 °C for 1, 3 and 5 h. In order
to determine the influence of the coal ash on the synthesis of tricalcium silicate 5, 10 and 15 wt. % of coal ash were added
to the prepared C3S mixture. The effect of coal ash was determined on composition of synthesis products and its
properties during hydration of samples. It was found that coal ash additive significantly changed the composition of the
products of tricalcium silicate synthesis that is essentially different from the theoretically calculated composition. It was
observed that in samples with 5 % of coal ash additive formed amount of dicalcium silicate was larger three times than it
had been calculated by Bogue method. However, the compressive strength of these samples (42.35 MPa) was higher to
compare with alite samples and only slightly lower than samples of pure tricalcium silicate.
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