Summary_Reader Response Draft #2: Coal ash into concrete

The NaturalBlaze.com article, "Researchers Turn Waste from Coal Power Plants into Concrete" (2019), reports that researchers from Drexel University have discovered a sustainable solution to protect the natural environment and improve the built environment by recycling coal ash. Coal ash, a harmful byproduct of coal-fired power plants, ends up abundantly in landfills each year. Concrete is one of the most popular building materials in the world but one drawback is that it requires the right atmospheric conditions. The article states that by turning these waste coal ash into a special additive, “spherical porous reactive aggregate” (SPoRA) and adding them into the concrete while curing process, it will improve the durability and quality of the concrete (as cited in the journal “Cement and Concrete Composites”). By using this method, it will reduce the number of coal ash in landfills and benefits the industry.

While I agree with the statement of using SPoRA in concrete reduces cost and benefits the concrete industry based on the points elaborated in this article, I have found the lack of information regarding types of SPoRA, and what time is suitable for the contractors to use it. 

The coal ash lowers the hydration temperature of concrete and prolongs the setting time. Especially in hot weather, this can be very helpful. But based upon the particular needs, some concrete contractors may view slower set times and longer cure times as a liability. They might want the concrete to set faster because it saves labor costs by reducing man-hours. Perhaps the weather is getting cold and they need the concrete to set more quickly to avoid freezing. Therefore, it will be the best if the researchers add the admixtures to the SPoRA and separate them into sub-groups depending on the places they can be used.

And the structural effects of coal ash may be more critical, but cosmetic concerns also affect its use in concrete. VandeWater (2016) states that it is more difficult to control the color of concrete containing coal ash than mixtures with Portland cement only and the color charts will not be completely accurate. Coal ash also may cause visual unpredictability in the finished surface, such as dark streaks from carbon particles. For this reason, the researchers should announce the warning that it will be a good idea for the contractor to make a mock-up sample before he use it.

Moreover, smaller builders and housing contractors may not be familiar with coal ash products, which can have different properties depending on where and how it was obtained. The poor quality of coal ash can increase the permeability of the concrete and cause damage to the building. Although coal ash in concrete is great in many applications and improves performance in some ways, but it also has some disadvantages.

References

VandeWater, S. (2016, April 16). How Fly Ash Can Affect Concrete Color and Performance. 

Retrieved, Feb-02-2020 from 

https://indecorativeconcrete.com/pros-cons-of-fly-ash/

Wilder, C. The Disadvantages of Fly Ash in Concrete. 

Retrieved, Feb-02-2020 from

https://www.hunker.com/13425141/the-disadvantages-of-fly-ash-in-concrete

Team McCoy Mart. (2019, November 29). What are the advantages and disadvantages of using Fly ash in Concrete?. 

Retrieved, Feb-03-2020 from

https://mccoymart.com/post/advantages-disadvantages-using-fly-ash-concrete/

Rodriguez, J. (2019, February 17). Uses, Benefits and Drawbacks of Fly Ash in Construction.

Retrieved, Feb-03-2020 from 

https://www.thebalancesmb.com/fly-ash-applications-844761