Quarries across Australia have the chance to make a significant contribution to the sand industry by engineering a sustainable material from by-product.
Concrete has been an industry standard construction material for 200 years.
It’s versatile and readily available. It also makes up around eight per cent of total global emissions, according to independent think tank Beyond Zero Emissions.
In addition, a key component of concrete is becoming harder to acquire – sand. The United Nations Environmental Programme estimates that sand extraction is rising at a rate it called “unsustainable”. It outlined the scale of the problem and the lack of governance, calling for sand to be recognised as a strategic resource, and for its extraction and use to be re-thought.
One of the companies helping solve this problem is Kayasand. The company was inspired by technology used in Japan to engineer sand for its construction industry following a ban on dredging in that country.
Related stories:
- Alex Fraser and Kayasand champion sustainability at IQA event
- Shifting sands with Kayasand
- Holcim levels up its sand plant with Kayasand
The technology has started to make waves in Australia and New Zealand, as engineered sand is put through its paces.
James Mackechnie, a concrete industry expert at the University of Canterbury in Christchurch, New Zealand has worked with concrete for most of his life.
He told Quarry about his laboratory testing of engineered sand.
“We have performed multiple trials in a laboratory setting. Replacing standard manufactured and natural sand with Kayasand’s engineered sand to see if there is potential for ready-mix producers,” he said.
“The results demonstrated a benefit in terms of cement efficiency. Less cement is needed to get the same strength in concrete with the Kayasand product.
“That’s a cost advantage and an environmental advantage – which is important because there’s immense pressure to be as economical as possible with cement in concrete.”
Kayasand’s plants can precisely control the shape and size of the sand particles, the levels of contaminants and consistency of the final product. Mackechnie said there were three main reasons the Kayasand product led to stronger concrete.
“Firstly, we need less water in the mix, which as a rule, makes concrete stronger,” he said. “There is also better packing density of the particles, so the resulting concrete has lower porosity and less voids than you’d expect to see.
“Lastly, engineered sand doesn’t have the potential for salt contamination that marine sands have, and which reduces the long-term strength of concrete.”
Kayasand’s manufacturing process is also dust-free, low-noise and uses no water for washing.
Kayasand engineered sand is made to the exact particle size and shape specified, using a process that removes contaminants and blends the product to the desired consistency at the plant prior to delivery.
Jason Chandler, director at Concrete Insights and 21-year veteran of the concrete industry, saw the potential in Kayasand’s technology.
“I’ve been involved with trials that Kayasand have done on Australian source material from across the country, testing the use of its engineered sands in concrete,” he said.
“Kayasand’s product is capable of not just replacing manufactured sand, but also the natural fine sand sourced from dunes and rivers.
“By using this engineered sand, I’ve been able to make concrete with a single source of sand that has an increased strength, reducing the amount of cement required by five to 15 per cent.
“The consistency of the Kayasand product also helps reduce variations in concrete strength. This enables concrete producers to lower their target strengths, which are typically set high to account for these variations. This in turn further reduces the amount of cement needed.”
Chandler set up Concrete Insights in part to help educate the industry about ways the industry could improve its sustainability.
One of the issues that other manufactured sands face is sub-optimal grading or shape, requiring the additional blending of natural sand into a final product.
This has led to the misconception that manufactured sands need to be blended with natural sand.
This is no longer the case – it’s possible to engineer sand to high standard that is fit for purpose.
Chandler said that forward-thinking companies are seriously considering the technology.
“Fine natural sand is increasingly hard to get, meaning you need to find an alternative supply from somewhere. We can’t rely on expanding dredging and mining operations to get more sand, so the Kayasand process makes sense,” he said.
“In my view, at some point the price of carbon will also become more and more critical. Cement is a big driver for carbon, and if you can remove five to 15 per cent with engineered sand, the economics will quickly pan out.
“Australia doesn’t currently have a formal price on carbon, but Europe is much further advanced on this. A lot of tier one contractors that work in our infrastructure industry are European and are starting to put pressure on their suppliers, including concrete manufacturers, to actively reduce their carbon emissions.
“In the past, the industry has benefitted from having easy access to plenty of material, but change is afoot, and the industry will need to incorporate innovations like this.” •
For more information, visit kayasand.com
.jpg)
