The National Highways Authority of India (NHAI) on Wednesday announced that it is considering the use of phosphogypsum waste material in the construction of national highways in order to promote a circular economy in the use of gypsum.

The NHAI is partnering with the Department of Fertilizers of the Ministry of Chemicals and Fertilizers to conduct field trials on projects that will use phosphogypsum for this purpose.

Phosphogypsum is a by-product of fertilizer production. The US Environmental Protection Agency identifies phosphogypsum as a waste product from manufacturing fertilizer that emits radon, a radioactive gas. It also contains uranium, thorium and radium — which are all radioactive elements.

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An Indian fertilizer company has already used the material to construct a road that was evaluated by the Central Road Research Institute (CRRI).

Based on the positive evaluation, the Indian Road Congress (IRC) has accredited neutralised phosphogypsum waste material for road construction for three years.

The NHAI is encouraging the use of waste plastic in road construction, a practice which has already been successfully tested.

Additionally, the NHAI has used fly ash, the fine residue of coal combustion in thermal power plants, for the construction of highways and flyover embankments.

The NHAI has been actively seeking out new, innovative materials to reduce the carbon footprint and make construction more economical.

By exploring the use of phosphogypsum and other waste materials, the NHAI is working to create a sustainable, circular economy in the construction industry.

With agency inputs.