Stepping on eggshells

Clay Technology magazine
30 Apr 2010
Inner tile layers with chicken eggshells

Scientists at Universiti Teknologi Mara, Malaysia, have transformed eggshell waste to create recyclable tiles suitable for decoration and design that they say may provide an alternative to ceramic tiles.

The EPoSTi tile is formed of polymer and crushed chicken eggshells. The researchers say the eggshell-based tiles, which have a high proportion of calcium carbonate, can stand up to 4.67 kN/mm2 of impact force, exceeding the ASTM qualified value of a tile and is highly stable when subjected to thermal testing. The eggshell has been shown to withstand temperatures of up to 750ºC providing safety against high temperature application.

Lead Researcher Dr Ahmad Zafir Romli who claims the strength of the material is due to the shells calcium carbonate content, explains, ‘Above 700ºC is the point where calcium carbonate usually faces thermal degradation, so this proves the high content of the calcium carbonate in the eggshell and its durability.’

According to Romli, the tiles, which are still at the pattern application stage, are simply processed. The eggshells are cleaned and mixed with the polymer in predetermined ratio and percentage. The composite is then filled into an air-ventilated mould and goes through heat-assisted curing, followed by removal from the mould and post-curing.

Researchers claim the tiles have the flexural strength to bend approximately 3% from its original dimension before breaking.

Romli, however, suggests the material will work as a cheaper alternative rather than an industry leading material. Highlighting the differences with ceramic tiles,
he says, ‘A ceramic tile requires extremely high temperatures to be cured, EPoSTi was fabricated at just boiling temperatures, so there is no complicated or high advanced technology in the production process. These tiles will not absorb heat as well as ceramics do, but 750ºC is a high enough value for a thermal safety application.’

The University claims to have produced souvenirs and paper weights from the eggshell composite and is now looking to develop the material for thermal roofing applications.

The next stage of research will look at developing the material to consist almost entirely of natural resource.