Concrete road kerbs and drains could be made with algae instead of sand, if a group of Singapore Polytechnic students’ final year project becomes commercially viable.
The School of Architecture and the Built Environment students found that a mix of algae and cement is strong enough for non-load bearing structures such as precast concrete drain sections, wheel stoppers in car parks and wall partitions.
And the students’ finding might potentially be the construction industry’s silver bullet, given recent bans on sand exports by neighbouring countries and the emphasis on sustainable construction methods.
Compared to sand, algae is freely available from water catchment areas here and is more environmentally-friendly. “The alkaline chemical in cement affects the skin and breathing in too much of cement particles makes your lung harden. Wet algae reduces these harmful effects,” said team member Athirah Rusli, 19.
She added: “Rather than incinerate the algae collected from cleaning up water catchment areas, algae’s binding strength can be put to construction use.”
Experimenting with various proportions of algae and cement, students found a mix containing 40 per cent algae and 60 per cent cement to be the strongest.
The students have yet to approach companies in the construction industry for commercialisation as they have just completed the project. However, they hope their idea will impress industry players at Singapore Polytechnic’s Engineering Show next weekend.
When contacted, construction firm Penta Ocean’s deputy general manager Desmond Hill commended the students for their efforts towards “sustainable construction”.
“In the old days, non-structural installations like drainages and road kerbs were made from recyclable aggregates like stones,” he said, but added that more studies on the long-term impact on algae’s use is needed.
“We need to assess the serviceability element - will the structure deteriorate after five years?” he said.
Concurring, Hexagroup’s project director Lim Hong Leong said: “For the product to succeed it must be priced lower than normal precast components and overcome the psychological barrier of being made from waste.”
A tonne of sand costs around S$42 per tonne now, down from S$60 per tonne at its peak four years ago when Indonesia banned sand exports. Ready-mix concrete, however, now costs S$109 per cubic metre, up from S$66 per cubic metre in 2007.
