Manufactured sand currently meets only a fraction of New Zealand’s sand demand, and naturally-sourced supplies will be required for many years to come, says the Aggregate and Quarry Association.
Natural sand, also known as river sand, is primarily used in construction for making concrete, plaster, mortar and asphalt.
AQA chief executive Wayne Scott says currently manufactured sand is meeting just 5 to 10% of New Zealand’s total sand demand, most of it for concrete production.
“There is no way manufactured sand can replace the need for natural sand in concrete. It will likely form an increasing percentage of supply, but it comes at considerable extra cost and, like any economic activity, has its own environmental consequences.”
He says most sand manufactured in New Zealand would need to be made from virgin rock or stone, as the crusher dust created from aggregate production is used in road construction.
“That means a lot of energy – either from electricity or diesel. If the sand has to be transported any distance, that further adds to environmental and economic costs.”
Scott says natural sand is sourced from coastal and river extraction or quarries – all of which have their opponents.
He notes that coastal-sourced sand is contentious in New Zealand, but in places like England, which have similar environmental protections, it provides 20% of supply.
“Most of the sand on coastlines comes from rivers and is replenished.”
Until recently, half of Auckland’s sand supply came from its north coast, barged into the city. With this supply now reduced by two-thirds following an Environment Court decision, many more trucks are now on the region’s roads.
Some of the alternative supply is river-sourced, which again can be controversial.
“Yet removing sand and gravel from rivers is a flood-protection measure – one which deluged residents, most recently in Tasman, urge their councils to undertake.”
Scott says, like many rock quarries, applications to extract sand are often opposed by nearby residents.
“Councils have to weigh up those voices against the need for a critical resource to support district growth. They certainly shouldn’t assume another solution is at hand.”
He says while manufactured sand will likely grow from its current 5–10% market share, it is no magic bullet.
“We will need a strong supply of naturally-sourced sand for many years yet.”