What is alkali activated slag?
What is alkali activated slag?
Alkali-activated slag (AAS) and AASC (alkali-activated slag concrete) are made by activating granulated blast furnace slag (GGBS) with alkali solutions. The hardened concrete has a denser microstructure with smaller and fewer capillary pores, resulting in enhanced ability to withstand chemical attacks [7].
What is the function of slag in blast furnace?
Pelletized blast furnace slag has been used as lightweight aggregate and for cement manufacture. Foamed slag has been used as a lightweight aggregate for Portland cement concrete. Granulated blast furnace slag has been used as a raw material for cement production and as an aggregate and insulating material.
What is alkali activated materials?
Alkali activated materials (AAMs) are binders, sometimes named geopolymers, that are produced through the reaction of an alkali source and aluminosilicates. The most commonly used alkali sources are sodium or potassium hydroxides and/or silicates, while aluminosilicates may include suitable raw materials and wastes.
What is alkali activated concrete?
Alkali-activated concrete (AAC) is defined as a class of cement-free concrete that is an alternative to Portland cement concrete (PCC). Instead of using ordinary portland cement (OPC) and water, AAC uses other supplementary materials like blast furnace slag (BFS) or fly ash (FA) along with an alkaline activator.
What is activated slag?
Abstract: Alkali-activated slag (AAS) is a promising alternative to ordinary Portland cement (OPC) as sole binder for reinforced concrete structures. OPC is reportedly responsible for over 5% of the global CO2 emission. In addition, slag is an industrial by-product that must be land-filled if not re-used.
What is the main use of slag?
Due to its positive technical characteristics, LD slag is used all over the world in road and railway construction and for engineering. The most common use is as an aggregate in the manufacture of asphalt. It is also successfully used as an aggregate for concrete.
What is the importance of slag?
While slags are generally used to remove waste in metal smelting, they can also serve other purposes, such as assisting in the temperature control of the smelting, and minimizing any re-oxidation of the final liquid metal product before the molten metal is removed from the furnace and used to make solid metal.
What are alkali activated binders?
Alkali-activated binders or geopolymer binders are hardened Page 2 compounds which acquire their strength and other properties by chemical reaction between an alkaline soluble source and aluminate-rich raw materials.
Is cement an alkali?
Alkalies in portland cement are comprised of the elements sodium (Na) and potassium (K). This is known as the “Equivalent Alkali” content and is often denoted as “Na2Oeq”. Na2Oeq is calculated as the sum of Na2O + 0.685 K2O. On a mill test report the “alkalies” are reported as “Na2Oeq” or “Equivalent Alkali”.
What are the advantages of slag?
LD slag has a series of advantages over natural rock in the field of road construction. Slag has a greater PSV (Polished Stone Value): i.e., greater resistance to wear. This is the result of its mineral composition. The consequences: less wear and longer road lifetimes.
How are alkalis carried up in a blast furnace?
Alkalis are volatilized as elements or react with C and N2 (nitrogen) in the bosh region of the BF forming vapours of potassium cyanide (KCN) or sodium cyanide (NaCN) as per reversible reaction 2K (g) + N2 (g) = 2KCN (g). The vapours are carried up along with the furnace gas and do not dissolve in the HM or into the slag.
What are the objectives of a blast furnace?
One of the main objectives during the operation of a blast furnace (BF) is to maximize the production of hot metal (HM) of the desired chemical composition at the minimum costs. This needs a high quality of a raw material base and a regular, smooth operation of the blast furnace.
What kind of cement is made from slag?
Our slag cement CEMSlag TM is a hydraulic cement material created when granulated blast-furnace slag from the steel manufacturing process is ground to a fineness suited for concrete production.
Why are alkalis bad for the Bf process?
The main unwanted elements present in the charge which can be troublesome with respect to removal and the performance of the BF are the alkali compounds of the metals potassium (K) and sodium (Na). In the BF process, the presence of alkalis is known to have negative influences on the process.