A blog about the availability, uses and sustainability of fly ash.
This blog is authored by the American Coal Ash Association (ACAA), a nonprofit trade association dedicated to advancing the management and use of coal combustion products.
We will use this platform to discuss issues related to fly ash and its availability, uses and sustainability. We hope you’ll join us in sharing information about this valuable resource.
The views expressed in this blog are those of ACAA and do not necessarily represent the views of any member company or organization.
The Benefits of Using Fly Ash in Cement
Fly ash is one of the most commonly used pozzolans in concrete and provides some very distinct advantages in the fresh and hardened state of concrete. Compared with most other supplementary cementitious materials (SCMs), fly ash has a lower water demand, improve workability and reduces bleeding.
Fly ash is often used as an alternative to Portland cement, adding strength to concrete mixes while reducing cost by replacing a portion of Portland cement. Fly ash can also be used as a filler for asphalt paving mixtures to improve performance characteristics such as rutting, stripping and moisture sensitivity.
From an environmental standpoint, fly ash can be recycled into new construction materials or used to help clean up contaminated sites. Additionally, using fly ash instead of Portland cement reduces the amount of CO2 emissions created during manufacturing by up to 20%.
Fly ash is the fine ash produced at coal-fired power plants that develops cementitious properties when mixed with cement and water. Fly ash in concrete is widely used across the U.S. to the strength of concrete. Fly ash use is also a sustainable practice that benefits the environment and industry economy as described below.
Availability:
Fly ash is typically produced from burning lignite or sub-bituminous coal and makes up about half of the total coal combustion product generated in the United States. Today, more than 55 million tons of fly ash are used annually in a range of construction applications and products, including concrete, grouts, soil stabilization, manufactured aggregate and fill materials.
Fly Ash for Concrete Production
Fly ash is a byproduct of coal combustion and contains a large amount of alumina and silica. It is often considered as an admixture to produce high-performance concrete because fly ash increases the workability, reduces the heat of hydration and improves the strength of concrete. Fly ash is produced at more than 150 operating coal-fired power plants in Michigan.
Fly ash can be used as either a supplementary cementing material (SCM) or as a substitute for portland cement in concrete mixtures. With fly ash, less portland cement can be used in the mixture, which lowers the total cost of concrete production, improves strength, durability and performance characteristics and reduces environmental impacts.
Fly ash is a pozzolan, a substance containing aluminous and siliceous material that forms cement in the presence of water. When mixed with lime and water, fly ash forms a compound similar to Portland cement. Fly ash can be used as prime material in many cement-based products, such as poured concrete, concrete block, and brick.
One of the most common uses of fly ash is in Portland cement concrete pavement or PCC pavement. Road construction projects using PCC can use a great deal of concrete, and substituting fly ash provides significant economic benefits. Fly ash has also been shown to improve some hardened properties of the concrete through pozzolanic activity, such as increased abrasion resistance and durability.
Fly ash is also being used increasingly for environmentally friendly manufacturing practices due to its ability to replace some of the Portland cement required in the concrete mix. The use of fly ash in place of Portland cement reduces greenhouse gas emissions by reducing the energy intensive clinker manufacturing process. It also reduces air pollution caused by the mining and transportation of raw materials for Portland cement production. This helps promote sustainable construction practices while providing additional engineering benefits to make better performing concrete products.
Fly ash is an environmentally friendly solution that meets or exceeds performance standards set by traditional Portland
NCL Industries Limited (NCL) was promoted by the Hyderabad-based Nalli Group in 1984. The company manufactures cement and refractories. It has installed capacity of 0.11 m tonnes for cement and 0.4 m tonnes for refractory products. The plant is located at Mattapalli in Nalgonda district of Andhra Pradesh, about 70 km from Hyderabad. The company’s cement division manufactures ordinary portland cement (OPC) under the brand name ‘Nagarjuna’.
In 1993, NCL Industries entered into a technical assistance agreement with Germany’s Lurgi GmbH for design and erection assistance for its refractory unit. In 1994, it entered into an agreement with Australia’s NRM Refractories Pty Ltd for technical collaboration, and also with Japan’s Shinagawa Refractories Co. Ltd to import magnesia bricks.
The company implemented an expansion scheme in FY97 to increase its cement production capacity from 0.2 m tonnes to 0.5 m tonnes per annum and to modernise the existing plant at a cost of Rs 1 bn.