Fly ash

Fly ash is a bi-product of burning of hard coal in power plants. Ground into the form of fine dust hard coal is blown into the boiler furnace and burnt at the temperature of over 1,200ºC.

Enriching cements with mineral admixtures is an integral part of the production process and is strictly controlled by our laboratory. Consistent quality and additional advantages of such cements allow for:

  • excellent plasticity and workability
  • extended application time of the mixture
  • ncreased concrete impermeability
  • enhanced resistance to chemical attack
  • ow heat of hydration during the set time
  • high final strength
  • stable parameters
  • reduced shrinkage

Clearly specified cement use is of great importance in the building process. There are different types of cements available on the building market, which have been designed for specific applications. Different cements have their own physical properties and they vary in terms of heat of hydration, set time, resistance to chemical attack and also reaction to ambient temperature. Not knowing the heat of hydration can have negative consequences. Significant differences between the surface temperature of concrete and the internal temperature might result in thermal stress. Thermal stress values exceeding concrete strength limit value set off the microcracking process, which results in reduced strength. The knowledge of various concrete setting times can be utilised by using CEM II cements with mineral admixtures in the summer in place of CEM I Portland cements of the same class. The quality of concrete products will remain the same, the workability of the concrete mixture will be improved and the economical and practical gains will be obvious. Most cement users are interested in high early-strength development. At early stages the highest compressive strength in a specified compression class is found in CEM I cements, while at a later time (periods of 28 and 90 days) the strength of CEM II cements with mineral admixtures is actually comparable with or even higher than that of CEM I cements.

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