SOURCE: Quarry Magazine | October 18, 202
Concrete has been used in construction for thousands of years, using sand sourced from dunes, rivers and seabeds.
However, as infrastructure demands and environmental pressure increases, access to high-quality natural sand has become more constrained.
Development of the vertical shaft impactors (VSIs) in the 1970s helped transform the commercial production of manufactured sand, unlocking a new source of high-quality material for concrete.
By enabling rock-on-rock crushing, it allowed quarries to produce higher-quality manufactured sand from quarried rock, reducing reliance on natural deposits and creating value from crusher fines.
However, times have changed and so too has concrete. Producers want greater consistency, improved performance and lower embodied carbon. So, does manufactured sand have to change too, or is it good enough as it is? For Kayasand the argument in favour of change is simple.
Two sands may have the same particle size distribution yet behave very differently in concrete.
Differences in particle shape, particle size distribution and the critical ultrafines fraction can influence water demand, cement demand and workability. Concrete producers must design mixes for the worst case, often using additional cement, water and chemical admixtures to ensure the required performance and consistent results. Kayasand chief executive officer Bram Smith said engineered sand focuses on controlling these characteristics.
“Rather than compensating for inconsistent sand with additional cement, natural sand blending and expensive admixtures, the aim is to simply make a good sand in the first place,” he said.
“From a quarry perspective, this evolution represents more than a technical improvement. It creates an opportunity to recover greater value from material that has traditionally been stockpiled as a lower value byproduct.
“Now, crusher dust becomes a premium construction material. It improves utilisation of the resource already being extracted from the ground and reduces our dependence on diminishing natural sand reserves.”
Performance data supports this approach. Kayasand trials using hornfels, basalt, granite and greywacke have demonstrated consistent improvements in concrete strength while replacing 100 per cent natural sand.
pending on the source rock and mix design, strength improvements of between eight per cent and 30 per cent have been consistently achieved, giving concrete producers greater flexibility over strength and cement requirements while maintaining target performance, and without compromising workability. Smith said quarries in New South Wales are already commercially producing engineered sand.
“This demonstrates that it is no longer limited to laboratory conditions or controlled trials. High-quality sand is being engineered consistently at scale to meet the exacting demands of modern concrete production. The technology is available now,” he said.
The performance improvements can also support sustainability. Better particle packing reduces unnecessary voids within the concrete, allowing cement to be used more efficiently.
Where less cement is required to achieve the same strength, embodied carbon is reduced and emissions lowered. At the same time, quarries recover greater value from existing resources rather than relying on additional natural sand extraction.
Smith said every major advance in quarrying has been driven by changing customer needs.
“Natural sand and manufactured sand blends have met the needs of their time. Engineered sand provides the next step in concrete sand evolution,” he said.
“Today, concrete producers are asking more of the materials that go into every mix. As those expectations continue to evolve, so too will the way quarries produce concrete sand.
“The opportunity is no longer simply to manufacture sand. It is to engineer the sand that modern concrete demands.”
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