Waste to Watch: Slag as an Aggregate

If you’ve been following our latest posts, then you know there is a growing interest in using various forms of waste in aggregate – learn more about seashells as an aggregate.

Some of the latest research published in Chemical Industry & Chemical Engineering Quarterly puts steel-making slag to the test using a factorial design approach.

The slag we’re discussing, a by-product of steel-making – much like how fly ash is a by-product of coal production – is used for a variety of applications.

Steel slag applications include

  • making asphalt aggregates skid resistant
  • soil treatments
  • road bases
  • railroad ballasts

However, many civil engineers are curious if this by-product could be used in addition to or in place of traditional aggregates. And they have good reason to be.

The researchers who initiated this study concluded that after 28 days of curing, the concrete made with steel-making slag compared equally to concrete made with traditional aggregate.

While further testing is necessary before steel-making slag becomes as permanent as Portland cement or fly ash, steel-making slag is cheap. If the coal demand continues to diminish thanks to natural gas and solar energy, alternative aggregate sources are going to become a sought-after industry.

What are your thoughts regarding steel-making slag? Do you believe there is a future for it?

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