Summary_Reader Response Draft #4: 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 to allow proper mixing and curing. 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 agreeing with the method of using SPoRA in concrete reduces cost and benefits the concrete industry based on the points elaborated in this article, the information regarding types of SPoRA, and the time, it is suitable to use are not stated in the article.
The 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. Federal Highway Administration (2016) states that there are two classes of fly ash for use in concrete: class F, usually derived from the burning of anthracite or bituminous coal, and class C, usually derived from the burning of lignite or sub-bituminous coal. The use of class F fly ash usually results in slower early strength development, but the use of class C fly ash does not enhance early strength development. The article also mentions the sources of ash which should be avoided to ensure the quality of fly ash for use in Portland cement concrete. The type of coal ash is important for the contractors as the coal ash lowers the hydration temperature of concrete and prolongs the setting time. 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.
The coal ash 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.
Although coal ash in concrete is great in many applications and improves performance in some ways, but it also has some disadvantages. Therefore, the article should indicate the information regarding types of SPoRA as it is important for the contractors.
References
Federal Highway Administration. (2016). User guidelines for waste and byproduct materials in pavement construction: Coal fly ash. Retrieved Feb-01-2020 from
https://www.fhwa.dot.gov/publications/research/infrastructure/structures/97148/cfa53.cfm
Researchers turn waste from coal power plants into concrete (Oct-29-2019). NaturalBlaze. Retrieved Feb-01-2020 from
Rodriguez, J. (2019, February 17). Uses, benefits and drawbacks of fly ash in construction.
Retrieved Feb-03-2020 from
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/VandeWater, S. (2016, April 16). How fly ash can affect concrete color and performance. Indiana Decorative Concrete Network. Retrieved Feb-02-2020 from
Wilder, C. The disadvantages of fly ash in concrete.
Retrieved Feb-02-2020 from
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