Singapore mines NewSand to overcome sand shortage

The Straits Times, May 15, 2007
By Imelda Saad, ST Interactive Reporter


FIRST Newater, now NewSand. Singapore may well have found an alternative to land sand in the production of concrete.

Fresh from Indonesia's sand ban, the Building and Construction Authority (BCA) is now working with a Swiss company that produces ready-mix concrete to create what's termed 'Eco-Concrete'.

Work is also underway to develop a code of industry standards which will specify guidelines for the use of recycled material in construction.

Eco-Concrete cuts back on the amount of sand used to produce concrete by 70 per cent - replacing it with copper slag, which is the waste material collected from the shipyard industry here.

The prospects look promising, the BCA believes, given the amount of copper slag that goes to waste in Singapore.

Some 400,000 tonnes of waste copper slag are produced by shipyards each year - equivalent to one month's supply of sand used by the construction industry here.

Copper slag is imported from Japan by the ship repair industry for blasting and cleaning vessels, and the used slag is discarded once the grittiness is lost.

In land-scare Singapore, most of the slag is dumped at the Semakau landfill with a nominal amount reused to construct pavements.

With Eco-Concrete, this discarded slag can be put to good use and could potentially lead to cost-savings for developers and contractors.

The BCA said Eco-Concrete is at least 10 per cent cheaper than normal concrete, which now costs $170 per cubic metre.

For now, BCA wants to promote its use in non-structural works such as the construction of roads, linkways, walkways and drains.

Further tests will be needed before authorites here give the go-ahead for Eco-Concrete to be used in structural works such as beams and columns of buildings.

Commisioner of Building Control Ong See Ho said: 'Currently we have allowed up to 10 per cent of natural sand to be replaced by washed spent sand copper slag to be used in structural concrete. To use waste and recycle material for structural concrete, we need to determine other issues to make sure they are of consistent quality, and also that they can meet the demand for strength - because we need to ensure that structural safety is not compromised.'

Mr Ong added through that tests so far have shown that the 'Eco-Concrete we produce will be able to meet the strength requirement'.

He said 'getting concrete at a cheaper price will be a good enough incentive' for developers and contractors here to make the eco-friendly switch.

Developer of Eco-Concrete, Holcim (Singapore) Pte Ltd is confident its new product can be expanded for use in structural works.

Vice-President of Operations Dr Sujit Ghosh said recycled material like copper slag could potentially replace up to half of the natural sand used in structural concrete, and 100 per cent of the sand used in non-structural works.

He said copper slag is 'better than sand' as it does not absorb water, and because it is not a 'naturally mined material', quality control of the product is also better.

The Straits Times Interactive understands that the BCA is working the Housing and Development Board to identify a project which can make use of Eco-Concrete in its construction.

This could be rolled out as soon as next month.