Environmental News, Materials Handling, Plant & Equipment

Is manufactured sand the future of concrete?

Manufactured sand is the economical and environmentally friendly substitute for the natural kind.

Concrete has a long history with humankind. The oldest known variant of concrete is approximately 12,000 years old and believed to come from the region we know today as Turkey.

It is a testament to humanity’s creativity and our desire to stay dry when it’s wet outside.

While ancient Romans used volcanic ash and other aggregate to create their concrete, today we use sand – a lot of it.

Roughly 40 per cent of a typical concrete mix is sand. Fifty billion tonnes of it is mined every year to meet concrete, glass and construction demand – that’s about 17kg of sand per person. It’s taken off the beach and dredged out of rivers and oceans.

In fact, sand is the world’s most widely used building material and our most used natural resource behind air and water. But it’s a finite resource and we’re running out of it.

The situation is so grave, the United Nations warned us of a global sand crisis in 2022.

So if there is a sand shortage, why aren’t we taking it from the desert?

Concrete sand needs to be of a certain coarseness to hold its shape. Smooth sand doesn’t bond well. This means, desert sand, worn completely round by the wind, is effectively useless for construction.

Luckily, there is a solution: manufactured sand.

And it is exactly what it sounds like. Crushed, screened and washed aggregate, or crusher dust, purposely made into a sand substitute for use in concrete, roading and a variety of other construction needs. It’s a high-volume, low-value product transformed into highly valued product.

The manufacturing process also happens to be more sustainable, environmentally friendly and economical than traditional sand mining.

For example, dredging for river sand – perceived to be the best sand for concrete – went mostly unchecked and unregulated until the 1980s, when the practice’s damning ecological consequences became apparent.

The downstream flow of sediment in rivers to fill holes caused by dredging hasn’t been able to keep pace with the rate of sand removal. This has led to riverbank and coastal erosion, and salinisation of sea water.

There is a growing concern about the impact on biodiversity of our waterways and the risk to populations living close to them, and this is making it harder and more expensive to get consents for future dredging operations.

Sand on the beach and from the ocean is much the same story. These are also affected by rising sea-levels, warming oceans and supporting an infinitely complex system of coastal and marine wildlife.

Realistically, mining sand straight from nature cannot support the growth in demand from the construction industry. Nor is it sustainable in the long term.

Luckily, manufactured sand fills this void, working just as well. In in some instances, it’s actually better and more reliable than the real thing.

A well manufactured sand is the right shape and size, and free from salt, clay, silt, dust and other natural impurities ordinarily found in natural sand. It is of a better consistency and increased workability and doesn’t suffer from honeycombing or voids when used to make concrete.

In fact, it makes stronger, more consistent concrete with fewer defects because it doesn’t contain any of the organic and soluble compounds that affect setting time and cement property.

In a report on the use of recycled aggregates in construction, Cement Concrete and Aggregates Australia investigated the efficacy of using manufactured sand as an alternative to natural sand.

“Manufactured sand can be used to replace a major proportion of natural sand with no significant loss of performance in cement-based products,” the report stated.

“Blending 50 per cent fine sand with manufactured sand produced more workable and generally superior concretes to those composed of fine and coarse natural sands.”

Even when in a mix, that’s still 50 per cent less sand being taken from the environment.

This is encouraging higher proportions of manufactured sand in concrete mixes over time, with 70–100 per cent now being reached in some cases. The goal is to consistently reach 100 per cent.

And the best part? It’s much more economical and better for the environment than sourcing natural sand.

Setting up operations in some remote part of a riverbed or beach is costly and technically challenging. And the cost of transportation can often outweigh the value of the sand itself. Conversely, manufactured sand is available anywhere there is a quarry.

Manufactured sand is the way forward. An economical and environmentally friendly substitute for the natural kind, it’s the construction industry’s answer to the global sand shortage.

Water management is also extremely expensive for the quarry industry, particularly in a flood and drought-prone country like Australia.

To learn more, visit kayasand.com

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