UNWANTED shells from palm nuts could be used to make concrete for buildings
and roads, solving a major environmental problem for many developing
countries.
Malaysia is the world鈥檚 largest producer of palm oil鈥攃ommonly used to
make margarine鈥攁nd generates 9 million tonnes of waste each year. This can
be incinerated or dumped, but neither solution is particularly 鈥済reen鈥�. However,
since the shells from oil-palm fruits are so tough, Abdul Mannan and C.
Ganapathy at the Malaysian University in Sabah wondered whether they could be
used in concrete.
Conventional concrete is a mixture of cement, fly ash鈥攑ulverised burnt
fuel from power stations鈥攁nd water. This forms a paste that binds with an
aggregate, such as sand or crushed stone. The idea is to use crushed shells as
the aggregate. But getting the proportions right is key. Simply swapping shells
for sand won鈥檛 work, as the resulting material will be too weak to be of any
use.
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The Malaysian team has hit upon a mixture that gives a lightweight concrete
that鈥檚 strong enough for low-rise buildings and roads. Importantly, the shells
do not rot once in concrete, and the properties of the palm-shell concrete match
those of ordinary concrete made with crushed stone.