Is fly ash a pozzolanic?
Origin of fly ash. These particles are termed fly ash and are collected from the flue gases using mechanical and electrical precipitators, or bag houses. It is this material that is used as a pozzolan in concrete and other cementitious products.
Why fly ash is pozzolanic?
Flyash is a pozzolanic material that in the presence of water and calcium hydroxide produces cementitious compounds. Flyash is a filler in hot mix asphalt applications and improves the fluidity of flowable fill and grout because of its spherical shape and particle size distribution.
What properties does fly ash have?
The four most relevant characteristics of fly ash for use in concrete are loss on ignition (LOI), fineness, chemical composition and uniformity. LOI is a measurement of unburned carbon (coal) remaining in the ash and is a critical characteristic of fly ash, especially for concrete applications.
What are the properties of fly ash bricks?
Comparison of Fly Ash Bricks and Clay Bricks
|S. No.||Properties||Fly Ash Bricks|
|2||Compressive strength||90-100 kg/cm2|
|4||Dimensional stability||High tolerance|
How does fly ash improve workability?
Improved workability. The spherical shaped particles of fly ash act as miniature ball bearings within the concrete mix, thus providing a lubricant effect. This same effect also improves concrete pumpability by reducing frictional losses during the pumping process and flat work finishability.
What is fly ash used for?
Among other applications, fly ash is used as material to make bricks, ceramic tiles, and plaster; as filler in metal and plastic composites and in paints and adhesives; and as structural fill for road construction. Flue gas desulfurization products rank as the second most abundant type of coal ash.
What is pozzolanic property?
A pozzolan is a siliceous or siliceous and aluminous material that in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds having cementitious properties.
What are the advantages of fly ash?
Advantages of Fly Ash It can add greater strength to the building. The concrete mixture generates a very low heat of hydration which prevents thermal cracking. Fly Ash concrete is resistant to acid and sulphate attacks. The shrinkage of fly ash concrete is very less.
What is the composition of fly ash bricks?
Fly ash bricks are lighter and stronger than clay bricks. Main ingredients include fly ash, water, quicklime or lime sludge, cement, aluminum powder and gypsum. Autoclaving increases the hardness of the block by promoting quick curing of the cement. Gypsum acts as a long term strength gainer.
What is the disadvantages of fly ash brick?
Disadvantages Of Fly Ash Bricks: It is very important to use only high-quality fly ash to prevent negative effects on the structure. 2. If not made properly, it has no strength and is not suitable for construction. Poor quality bricks have negative impact on concrete.
What is the problem with fly ash bricks?
Other prominent concerns of using fly ash bricks include: Slower strength gain. Seasonal limitation. Increased need for air-entraining admixtures.
What is the meaning of pozzolanic?
poz·zo·lan n. 1. A siliceous volcanic ash used to produce hydraulic cement. 2. Any of various powdered substances that react with lime to form strengthening or enhancing compounds in cement.
Is flyash pozzolanic or cementitious?
The flyash produced by burning of lignite or any other sub-bituminous coal may have CaO content more than 10%, hence this calss has both the properties of pozzolanic and cementitious. Because of its pozzolanic properties, flyash is widely used in the manufacturing of portland pozzolanic cement.
What are the properties of flyash?
Along with pozzolanic properties, flyash also has ceramic properties due to which it is widely used in the manufacturing of fly ash bricks. Bricks produced from flyash are generally superior in quality and have high compressive strength compared to ordinary clay bricks.
What are flyfly ash blocks?
Fly ash blocks are a building material, especially masonry units that are utilized in the construction of buildings. Fly Ash Bricks are used as the alternative material for burnt clay bricks for masonry works.
What is the thermal conductivity of fly ash bricks?
The thermal conductivity of fly ash bricks is nearly 0.90 – 1.05 W/m2. They absorb less heat. The pozzolanic effect between the fly ash and lime generates less heat.