Fly ash fineness - Comparing residue on 45 micron sieve with Blaine's surface area

With the help of laboratory data the paper proposes to make the test a mandatory quality control tool for using fly ash as a pozzolona.The quality of fly ash generated by coal fired Thermal Power Station shows a wide range of variation in both chemical and physical properties because both the quality of coal and the combustion condition of boilers vary. While supplying fly ash quantities, matching user’s specification is important; past investigations show that the pozzolanic properties of fly ash are not so much governed by the chemistry as by the mineralogy and particle size. Regardless of the fly ash type, particles under 10 micron are the ones that contribute to the 7 and 28 days strengths. Particles between 10 and 45 micron contribute to strength from 28 days and up to about one year. Particle above 45 microns are considered inert. They behave like sand particles. It has been reported that the particles below 10 microns govern the fly ash reactivity.