Kayasand engineers the future of sand

Kayasand founder Andi Lusty looks back at his career and why he believes the future of sand will be engineered.

Creating sand naturally can be a long and drawn-out process. To make it happen, rocks must undergo thousands, if not millions, of years of slow erosion via rivers and glaciers.

While this process is never-ending, most construction companies cannot wait for millennia.

Sand plays a vital role in the creation of concrete, which in turn is necessary for Australia’s infrastructure and houses.

However, as industry stakeholders look to embrace a sustainable outlook, it has become much harder to access natural sands close to urban areas and construction projects.

Kayasand founder Andi Lusty told Quarry that this has been a problem facing the industry for more than 30 years.

“In the early 90s, there was demand for manufactured sand to be used alongside natural sand, as the supply of natural sand was getting harder to access. Companies at the time turned to crusher dust, a waste product in most quarries, and wanted to find a way to use it,” he said.

“They noticed there was an improvement in the strength of concrete when adding crusher dust to the concrete. Too much of it though, and you ended up with a bony concrete that was hard to finish and needed more water.

“The Barmac excelled at supplementing natural sand due to the way it shaped the crusher dust.”

Lusty has been involved in the crushing industry for decades. He moved to New Zealand in 1981 from the UK to sell Barmac vertical shaft impact (VSI) crushers.

The crushers use ‘rock on rock impact’ to produce a quality cuboid product that could replace up to 60 per cent of the natural sand required in concrete.

Japanese innovation

While this manufactured sand was helpful – it still had its limitations. It could not create 1mm particles, had too much ultrafines and required more water in concrete. The availability of sand diminished each year, particularly fine sands that were -1mm that was perfect to blend with Barmac sand. However, limited availability meant the natural sand on the market could only supply so many projects,

Lusty said concrete manufacturers were trying to increase the amount of manufactured sands in their blends.

“Everyone had their own versions of manufactured sand, and because they were all so different, it meant you couldn’t trust it,” he said.

One of the Barmac distributors in Japan, Kemco, saw this firsthand when the government banned dredging. That’s when Kemco chief engineer Takato Kaya saw an opportunity.

Kaya invented a new crusher with a proprietary air screen that uses autogenous crushing in the particle cloud and on the rock bed. When used with a secondary impact zone, the crusher creates sand that is excellent in shape, and the air screen accurately controls the volume of ultrafine -75 micron particles in the sand. The resulting sand used less water in concrete.

Kemco launched the technology in the early 2000s. Since then, it has been a huge success, with around 60 Kemco V7 plants operating in Japan and more than 100 in China.

Inspired by Kemco’s technology, Lusty retired from selling Barmac VSI crushers, founded a new company to sell the Kemco technology, and named it Kayasand, after the technology’s inventor.

Engineered differences

Kayasand’s plants can precisely control the shape and size of the sand particles, thanks to the grinding impact action that mimics natural erosion. This creates a cuboidal particle that is ideally shaped for strength and workability in concrete.

The material is then fed into a combination of a high-accuracy screen with high throughput air classification to ensure the product meets specifications.

Water and skimmer material are blended into the final product to maximise concrete performance and suppress dust on the stockpile. Ultrafines are extracted and stored dry until needed to dose other quarry products or loaded into trucks and tankers.

This process optimises the shape of the product, removes contamination, and has high levels of product consistency.

Lusty said the company’s product can be used to replace 100 per cent of the sand required in concrete and can be used to create even stronger concrete than natural sand.

Last year, Kayasand put its product to the test in a concrete trial. Sand engineered from Greywacke-based crusher dust replaced 100 per cent natural sand in a normal Auckland concrete mix. The resulting concrete proved to be 24 per cent stronger and used up to 10 per cent less cement. The goal is to reduce cement requirements by 20 per cent.

“Our sand isn’t just any old, manufactured sand – it’s Engineered Sand. We want people to understand the product we are helping create is precision engineered for concrete,” Lusty said.

One of the challenges the company faced with this new technology was an industry that was hesitant to invest in new technologies. However, in recent times, Lusty said there has been an uptick in interest in the technology for three reasons.

“The first is the need for a natural sand replacement. The second is they have been seeing it operate for many years now. The third reason is that from our testing, they have been able to see cement savings that would quickly pay for the plants,” he said.

“They can see the return on investment and clear advantages. There’s also a lot of younger talent that have come to the industry with new ideas.

“They’re now looking at it as an investment that can save them thousands on sand and cement but could also improve their emissions reductions into the double digits. It’s turning heads.”•

For more information, visit kayasand.com