Researchers Develop Sustainable Concrete from Coal Waste

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Researchers from the Washington State University (WSU) created a sustainable concrete using coal fly ash

The research conducted by Washington State University and published in the journal Fuel on April 24, 2018 reported the influence of graphene oxide in chemically activated fly ash. The development addresses a couple of major environmental problems by significantly reducing the environmental impact of concrete production and by making use of coal production waste.

Concrete is conventionally manufactured by combining cement with sand and gravel. However, the key ingredient in concrete, requires high temperatures and a tremendous amount of energy to produce and the process contributes around five and eight percent of greenhouse gas emissions worldwide. Fly ash is a byproduct that remains after coal dust is burned and contributes to a significant waste management issue in the U.S with over 50% of fly ash depositing in landfills.

Xianming Shi, associate professor in WSU’s Department of Civil and Environmental Engineering, and graduate student Gang Xu created concrete at the molecular level using nano-sized materials. The reaction of fly ash with water is manipulated by graphene oxide— a nanomaterial that alters the activated fly ash into a strong cement-like material. The graphene facilitates rearrangement of atoms and molecules in the solution of fly ash and chemical activators (such as sodium silicate and calcium oxide). The resulting molecule is a chain of calcium-aluminate-silicate-hydrate with strongly bonded atoms. These chains form an inorganic polymer network that is more durable than conventional cement. Moreover, pervious nature of the fly ash concrete facilitates water to pass through it that replenishes groundwater and mitigate flooding potential. The strength and behavior of the material was tested by the researchers on the WSU campus under a variety of load and temperature conditions. Furthermore, infiltration tests are being conducted to gather data using sensors buried under the concrete. The team plans to patent the technology for its commercial use.

 

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