Pond ash is a by-product of the works in power plants. It has several applications in civil engineering mainly in the construction sector. In this blog, we will go through the basic details, properties, applications and limitations.
Let’s start from scratch.
What is pond ash?
- Furnace bottom ash (FBA) is a waste material, it generally has no pozzolanic property, and hence it cannot be utilised as a cement substitution material like fly ash.
- On the other hand, its grain size distribution is like that of sand(CA)
- So it can be utilised as a sand substitution material.
- Pond ash is a waste product from coal-based power plants.
- Ash pond is a pond developed in the power plant area to store ash.
Now, you know the basics. In the section, I will show you the importance of pond ash.
Why we should use pond ash?
- Concrete is one of the most important materials in building construction and other infrastructure works.
- The studies say that the need for concrete will increases further to almost 7.5 billion m3 (about 18 billion tons) a year by 2050
- At least three-quarters of the total volume of concrete consists of coarse and fine aggregates.
- Natural resources such as river sand are getting depleted.
- The power required for the country is rapidly increasing
- In India, Coal-fired thermal power plants fulfil about 65% of the country’s electricity requirements.
- The coal-fired thermal power plants burn about 407 million tons of coal.
- And produce about 131 million tons of coal ash annually from which 15–20% ash is bottom ash and the balance is fly ash.
- It forms fine particles less than 4.75mm.
- As the accumulation in the pond ash (PA) around the thermal power plant is posing threat to environmental, its proper management is becoming essential.
- It is found that it is possible to replace some per cent of sand by pond ash as fine aggregate in concrete without compromising on strength and durability.
Time to see the technical details on the workability.
Workability of pond ash concrete
- In general, the workability of the material reduces with the increase in percentage of fine aggregate replacement.
- Due to the specific surface effect of the mixture and also probably due to the higher water absorption capacity of PA.
- But on combined grading and use of proper plasticizer, workability can be restored to a large extent.
- In fact, PAC mixes were better than conventional concrete mixes due to the increased cohesiveness and total absence of bleeding.
Next we will find out the benefits of this material.
Benefits of pond ash
- To provide economical concrete.
- For effective waste management.
- To reduce cost of the construction
- To find optimum strength of partial replacement of concrete.
- To Minimize the maximum degradation in the environment due to pond ash.
After all the positives, the topic is incomplete without siting the disadvantages.
- Cause severe respiratory problems
- Visual and aesthetic problems in almost all the major industrial cities in India
- Degradation in the environment
- Depletion of the natural resources
- Ash pond areas lose all vegetation and the area never can be reclaimed for irrigation.
- The ash bunds collapse and contaminate freshwater resources.
So, let’s wrap up.
- The density of concrete reduces with the increase in percentage of pond ash.
- The compressive strength of concrete with pond ash increases with increased curing.
- The split tensile strength of concrete with the material increases up to the addition of20% ash sand replacement.
- The flexural strength of concrete with pond ash increases upto the addition of 20% ash sand replacement.
- While the material is used the workability is reduced. For obtaining the required workability super plasticizers are added.
- With increasing replacement of fine aggregate, linear reduction due to low relative_density.
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