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Times 17 Sep 07
HDB move to cut concrete use pays off
It adopts alternative materials and techniques following Indonesian sand ban
By Arthur Sim
STEEL, aluminium and even glass are to be the new concrete for many of the Housing and Development Board's latest projects.
Materials and techniques which might not have been cost-effective in the past have become increasingly viable following the rise in the price of concrete caused by January's ban on exports of sand from Indonesia.
The HDB says that initiatives it has already taken, such as using steel instead of concrete to construct lift shafts, have already achieved positive results.
The HDB told BT that using steel in a conventional 12-storey block has reduced the amount of concrete needed for lift shafts by 90 per cent. 'This leads to an overall cost savings of about 20 per cent and a shortening of construction time by 20 per cent,' a board spokesman said.
A conventional 12-storey concrete lift shaft can require up to 90 cubic metres of concrete. This new method of construction was piloted in projects in Yishun, Jurong East and Marsiling and the HDB says that since April, use of the technique has been extended.
Another upside of the new method is that an additional 250 blocks which previously exceeded the budget for the Lift Upgrading Programme now become eligible.
Following the sand ban, the HDB - probably Singapore's biggest developer - said that it would try to cut the use of sand by as much as 30 per cent. By volume, sand is the main ingredient of concrete.
'While engineers work towards economising on materials and designs, architects will continue to ensure that the outcome retains its desired aesthetics and functionality,' said the HDB. Building layouts and structures are being fine-tuned to optimise concrete usage.
But some of the new architecture-led initiatives include the simple tweaking of previous HDB design guidelines.
One new idea involves providing much larger glass windows. The HDB has been providing bay windows in flats since 2004. 'Taking this a step further to improve economy and reduce sand use, we now provide three-quarter and full-height glass windows for bedrooms and living rooms respectively,' the board said.
Other simple solutions include changing the design of concrete parapets along corridors. Since 2000, most parapets have been built using perforated aluminium panels. HDB says that all HDB buildings tendered from June onwards will have parapets designed with slits or perforations to reduce the concrete use - or simply have metal parapets.
Other solutions involve replacing concrete designs with metal ones. For new shelters and linkways, HDB plans to use steel columns instead of concrete. Modular steel ramps were tried out at Woodlands Street 83 and will be introduced to more HDB estates in line with its Barrier Free Access initiative.
The HDB said: 'As the industry exploits new materials, methods and technology in our move towards sustainable construction, we believe home buyers will also grow more receptive to the use of these new materials and designs.'
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