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Pulverized Fly Ash (PFA) VS GGBS

27 Jun,2022 UTC+8 Views:


The difference in source materials:
PFA is the finely divided mineral residue resulting from the combustion of powdered coal in electric generating plants, whereas GGBS is obtained by quenching molten iron blast furnace slag in water or stream, to produce a glassy granular product that is then dried and ground into a fine powder.
The difference in chemical compositions:
PFA usually contains very high SiO2 and Al2O3, but very low in CaO (accounted for 1-5% only), whereas GGBS has very similar chemical compositions to Ordinary Portland Cement (OPC) such as 30-42% of CaO, 35-38% of SiO2, 10-18% of Al2O3, 5-14% of MgO etc.
The difference in hydration activity:
PFA is not a hydraulic material, hydration will not take place on its own, and it will only harden with the use of activators (e.g. OPC). GGBS, in contrast, is a hydraulic material, which means that it will set and harden due to a chemical reaction with water. After hardening, it will retain some strength development and remain stable even under water. Concrete containing GGBS cement has a higher ultimate strength than concrete that uses 100% Portland cement.
The difference in the permitted replacement ratio:
The permitted replacement ratio of PFA in OPC is 20-40%, but it’s usually no more than 35% in concrete. On the other hand, the permitted replacement ratio of GGBS in OPC or concrete is 20-70%. It could even be replaced up to 85% in some of the European countries.
The difference in usage
To ensure the strength of concrete meets the requirement, the amount of PFA used is usually more than the amount of OPC being replaced. GGBS, in contrast, is used in the equivalent amount to OPC being replaced, and yet the requirement on strength could still be met.

GGBS grinding plant.jpg
Therefore, it is more suitable to use GGBS as an excellent binder for cement and concrete. CHAENG can undertake EPC turnkey services for GGBS production line with an annual output of 200,000-1,500,000 tons. Welcome to consult online or leave a message. 

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