What does Ggbs do to concrete?
What does Ggbs do to concrete?
GGBS cement prevents the occurrence of efflorescence, the staining of concrete surfaces by calcium carbonate deposits. Due to its much lower lime content and lower permeability, GGBS is effective in preventing efflorescence when used at replacement levels of 50% to 60%.
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 an alkali activator?
Alkali-activated system components (Garcia-Lodeiro et al., 2015). Precursors are defined as the main product of hydration in the binders. The main precursors used are based on AAS and FA calcium-silicate-hydrates and complex amorphous gel, such as alumina-silicate gel. CaO, SiO2 and Al2O3 contents > 20%.
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 Portland cement can be replaced entirely, thus offering a substantially reduced environmental impact over conventional concrete.
What is the difference between fly ash and Ggbs?
There is a wide variation in the chemical properties of fly ash and GGBS. Fly ash is low in calcium oxide content but rich in silica and alumina while GGBS is relatively high in calcium oxide. The combination of these two materials can be more beneficial when used as a stabilizing agent than using them individually.
What is the difference between geopolymer and alkali activated cement?
Generally in the literature, the ligands with precursors based on alumina and silica are treated as geopolymers, while alkali activated cement are based on precursors rich in calcium.
What are 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 binder?
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.
How do you make an alkaline solution for geopolymer concrete?
6 M to 12 M of NaOH solution and sodium silicate in acquis form (containing 50% water) are used in ratios (called alkalinity ratio Na2SiO3/NaOH = 1 to 2.5) to form a alkaline solution for geopolymer.
How do you activate slag?
Most applications employ the use of high pH values in the pore solution (> 13.0) to accelerate the corrosion of the glass network of the slag. It is shown in this work that activation is also possible by lowering the pH to a range between 11.8 and 12.2 by the addition of calcium hydroxide and soluble calcium salts.
What is the chemical composition of fly ash?
Fly ash is predominately composed of silica, aluminum, iron, calcium, and oxygen, but the particles may also contain heavy metals such as arsenic and lead at trace levels. Most nations throughout the world do not consider fly ash a hazardous waste and therefore regulations on its disposal and storage are lacking.
