Granulated Blast Furnace Slag (GBFS) is a by-product of steel manufacturing. Iron is extracted from iron ore, which takes place in a blast furnace where the ore, limestone or dolomite, and fuel (coke) are introduced into a furnace to effect the separation of the molten iron from the impurities. When taken out of the blast furnace, slag is in a molten condition. Granulated Blast Furnace Slag is formed by rapidly quenching the molten slag with large amounts of water.
Fly Ash is a byproduct of the power generation industry obtained by the mechanical or electrostatic precipitation of powdery material derived from the combustion gases in a boiler fed with pulverized coal. They are made of spherical vitreous particles and may have pozzolanic properties. Fly Ash can be used as an alumina and silica source in the raw mix in the process of cement manufacturing.
Silica fume, also known as MicroSilica, is a byproduct of producing silicon metal or ferrosilicon alloys. The main ingredient of silica fume is amorphous (non-crystalline)silicon dioxide. The individual particles are extremely small, approximately 1/100th the size of an average cement particle. Its average granule diameter is 0.15~0.20 μm, specific surface area is 15000~20000m2/kg. Because of its fine particles, large surface area, and the high SiO2 content, silica fume is a very reactive pozzolan when used in concrete.
Pozzolans are silicate-based non-crystalline materials that react with the calcium hydroxide generated by hydrating cement to form additional cementitious materials. Depending upon the particle size, chemical composition and dosage, different pozzolans will affect the concrete strength and performance differently and at different times during curing. Pozzolan was first found near Naples, Italy.