engleski

Fly ash as an active mineral addition to Portland cement and concrete

In the few decades, much research has been directed towards the utilization of industrial waste materials (slag, silica fume, limestone dust, fly ash) in cement or in concrete. When these wastes, as mineral additions, are added to cement/concrete, they modify the properties of fresh and/or hardened cement hydration products. The present work has examined the physical, chemical, compositional and pozzolanic properties of fly ash, emerging as a by-product of the combustion of coal in coal-fired power plants (the Thermal Electricity Station Plomin 2, Croatia), and the quality requirements for fly ash for use as a mineral addition in Portland cement and concrete. A number of techniques including XRD, IR spectroscopy, TEM and TG/DTG have been used to determine the characteristics of the fly ash used. Several methods, based on the analysis of the pozzolanic reaction in lime-fly ash and cement-fly ash systems, have been applied to evaluate the pozzolanic activity of fly ash. The results have shown that fly ash belongs to the ASTM Class F type (with a low content of CaO) and exhibits pozzolanic properties. The knowledge of fly ash properties will help provide a better understanding of the factors that control their performance in concrete. Therefore, further research is certainly needed to fully elucidate the effect of fly ash on the mechanical properties of concrete.

Waste management; fly ash; Portland cement; hydration; pozzolanic activity.

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