"True and False" Fly Ash Big pk

False fly ash is generally used by merchants to grind the slag or coal gangue or limestone from thermal power plants and mix it into fly ash. This adulterated fly ash is from the appearance and color. There is no obvious difference between real fly ash, and its chemical composition (CaO, SO3 content, loss on ignition, etc.) and physical indicators (volume stability, moisture content, water demand ratio and activity index, etc.) are not much different, however, under a microscope of more than 100 times, the core material of fly ash, that is, glass spheres, is basically invisible. The activity index of this adulterated fly ash is extremely low or has no activity at all. The water demand in the mixing concrete is large, and the fluidity and pumping effect are not as good as real fly ash. It also has a great adverse effect on the strength and durability of the concrete, and the surface of the concrete is dull and.
Normal fly ash belongs to spherical glass body. Even after being ground by a ball mill, the crushed particles are like crushed pebbles. There is a non-crushed surface but it is still spherical. False fly ash is basically a crushed surface like crushed stones, and the shapes of the particles are clear and clear.
For fly ash mixed with limestone or dolomite, dilute hydrochloric acid can also be used for inspection. The method is very simple and intuitive. The specific method is: weigh about 10g of dried sample and put it into a clean beaker, first add 50mL of distilled water and fully stir, then add about 10mL of dilute hydrochloric acid. If a large number of bubbles (I .e. carbon dioxide gas) are generated, it is proved that the fly ash is mixed with limestone material. This kind of fly ash mixed with limestone or dolomite is often white in color, with a very large loss on ignition, generally above 25%, and its activity index is significantly lower than that of true fly ash or has no activity at all.
For adulterated fly ash, chemical analysis can be used for inspection and identification. This method is more