Recycled limestone waste will soon be on the market for building after 10 years of research, offering a possible solution to the challenges faced by the construction industry.

A decade of laboratory testing by architect Franco Montesin and Dion Buhagiar established that the properties of the recycled stone are similar to, if not better than, globigerina limestone, meaning low-rise residential buildings could be constructed from this material.

Globigerina limestone for building is an increasingly limited resource and is undervalued, Buhagiar pointed out. But the recycled version competes well with the Äˇebel tal-franka.

“It seemed wasteful to dump inert demolition waste into disused quarries,” Buhagiar, associate professor in the Faculty for the Built Environment, said about the driving force behind the University of Malta ReStone project, aimed at reusing building waste.

The prototype engineered stone has been in pre-commercial production for the last few years and is scheduled to be commercialised next spring.

“Efforts are underway to finalise the manufacturing line processes to commercialise this product and, once completed, production will start,” Buhagiar announced.

“It has taken us 10 years to reach this stage of development primarily due to the importance of determining the stone’s durability performance,” he said about the work of 15 Master’s students.

Recycled stone can be engineered for use

Tests were carried out to determine its properties, including strength, impact resistance, water absorption characteristics and durability against salt crystallisation.

But the most significant hurdle was how to best optimise the mechanical properties of the recycled stone, Buhagiar said.

“Given that we use a patented process for production, we can now confidently produce recycled stone with differing mechanical properties.

“In essence, recycled stone can be engineered for use,” he said, adding that its properties allow for “new possibilities that positively contribute to the environment”.

What are the benefits?

Among the benefits is also the possibility of introducing modular construction, incorporating recessed channels for conduits and doing away with chasing for plumbing and electricity, thereby reducing dust and air pollution.

The recycled stone also addresses essential sustainability and waste management aspects of the building industry,  Malta’s single biggest generator of waste, Buhagiar continued, pointing also at the lack of disused quarries available for dumping.

The research was possible thanks to the financial assistance of the Malta Council of Science and Technology, Indis Malta Ltd, the university, the support of its Knowledge Transfer Office and the collaboration of Halmann Vella. 

It has been hailed as “a great achievement” and “some good news for the industry” by architects.

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