High Early Strength Fly Ash Concrete for Precast

It isn’t often that you can equate coal-related products with energy efficiency, but when it comes to fly ash, it actually does help. This fine powder byproduct of coal plants is often used to replace natural materials in the production of concrete.Using fly ash reduces CO 2 emissions. In fact, for every ton of cement replaced with fly ash, nearly one ton of CO 2 is kept from entering the

They are used extensively on larger projects where reinforcing steel requires high workability. Also used in precast and on site where the large water reduction provides very high early strength and improved durability. Water reducing additives usually reduce the required water content for a concrete mixture by about 5 to 10 percent.

High-early-strength can be obtained by using one or a combination of the following, depending on the age at 301 Chapter 17 High-Performance Concrete which the specified strength must be achieved and on job conditions: 1. Type III or HE high-early-strength cement 2. High cement content (400 to 600 kg/m3 or 675 to 1000 lb/yd3) Table 17-3 (Metric).

As multistoreyed construction is the need of today, high strength concrete is going to replace normal concrete.

Of the 38.2 million tons of fly ash produced, only 14.1 million tons are used in concrete. Fly ash is the most plentiful of all SCMs and is roughly half the cost of portland cement. However, because of increased emissions regulations on coal-fired power plants, not nearly as much high-quality fly ash is produced as in the past.

When mixed with lime and water, fly ash forms a compound similar to Portland cement. This makes fly ash suitable as a prime material in blended cement, mosaic tiles, and hollow blocks, among other building materials. When used in concrete mixes, fly ash improves the strength and segregation of the concrete and makes it easier to pump.

Effect of sand replacement on the early age strength gain and long term corrosion resisting ; characteristics of fly ash concrete, ACI Materials Journal, Jan-Feb (1989) 58-62. Swami, R.N., Sami A.R. Alli and Theodorakepoulos D.D, Early strength fly ash concrete ; for structural application, ACI Material Journal, Sept-Oct (1983) 414-422

This is inferred that calcium-bearing mineral phases of high calcium fly ash work as a reactive additive than an inert filler, giving a higher early strength comparable to control concrete that is unlikely to happen when the low calcium fly ash is used.

consisting of the concrete specimen containing cement 15% with MK and Fly ash at 5% to 20% and using M.Sand as fine aggregates was carried out. Addition of MK and Fly ash had resulted in improved strength at initial ages and ultimate concrete strength. Fly ash 15% and MK by 20% replaced for cement, showed better results than the other mixes. 6.

High Performance Concrete (HPC) is more homogeneous than normal strength concrete (NSC). HPC does not simply mean high strength concrete (HSC), but also includes other enhanced material properties such as early-age strength, increased flow ability, high modulus of elasticity (MOE), low permeability, and resistance to chemical and physical

EverPlus Fly Ash Class C. High Strength Concrete (HSC) has been developed over the past several decades, prepared by introducing water-reducing admixtures and high strength cementitious materials. Precast concrete is produced by casting concrete in a reusable mould or form, and is widely popular throughout NZ’s construction industry