Bird Nest Inspires Engineers to Build New Bricks from Plastic Waste

A new brick made from domestic plastic waste has been proven to provide 10 times better insulation than traditional bricks made from clay.

Dr Karthikeyan Kandan, senior lecturer in Mechanical Engineering at De Montfort University Leicester (DMU), has created a novel brick made entirely from upcycled plastic waste.

Believed to be the first of its kind, the brick is constructed using 3D printing and lattice architecture technologies, which involves criss-crossing strips of the plastic materials to form a grid or weave.

The design is inspired by nature, after Dr Kandan examined the structure of the Baya weaver bird’s nest; renowned for its elaborately woven construction.

“The Bayer weaver bird’s nest’s ingenious construction gives it excellent thermal insulation and mechanical properties for inhabitation,” explained Dr Kandan.

“Inside there is a central nesting chamber, which makes it the ideal micro-climate for inhabitation. By replicating this structure, we have manufactured a brick that improves energy efficiency of modern buildings and therefore can reduce carbon foot print.”

Saad Alqahtani, a first-year PhD student at DMU, carried out controlled experiments on the plastic bricks, under joint supervision from Dr Kandan and Dr Farukh – also a senior lecturer in Mechanical Engineering at the university.

To test its thermal insulation characteristics, Saad placed the brick in a hot-box calorimeter – a piece of equipment used to measure the U-value of an object, which can be set up to simulate the regulatory standard for buildings.

U-value is a measure of the flow of heat through an insulating or building material: the lower the U-value, the better the insulating ability.

The results showed the new design delivered an impressive U-value of 0.25 Watts per Metre Kelvin (W/m²K). This is 10 times more effective than a clay brick, which delivers an average of 2.94 W/m²K.

Traditionally, a range of building blocks are required to achieve the regulatory standard U-value, however, the newly designed plastic brick can achieve this on its own.

“Our brick, made from all kinds of domestic plastic waste – from coffee cup lids to plastic bottles – exhibits a tremendous thermal envelope over conventional building materials,” said Dr Kandan.

A building envelope refers to the exterior elements that protect the property and its inhabitants from the elements and also contributes to keeping the building structurally sound.

“This provides significant potential to not only improve the energy efficiency of modern building, but also to conserve space and reduce dead-weight in multi-story buildings,” added Dr Kandan.

Saad, who received a PhD scholarship from DMU to complete this work with Dr Kandan and Dr Farukh, said their brick could lead to a new era of energy-efficient construction while tackling the issue of plastic pollution at the same time.

“Our work has demonstrated that 3D printed bricks made from household plastic waste are thermally far superior than the existing bricks made in the market,” he explained. “This breakthrough can literally help us build the future.”

This project marks the second time this year that Dr Kandan has been recognised for his work to repurpose plastic waste. In August he made headlines when he created a prosthetic limb socket made from recycled plastic water bottles for amputee patients.

Saad, who also completed his MSc at DMU, was invited to showcase their work at the prestigious 39^th International Workshop on Computational Mechanics of Materials in Dubrovnik, Croatia, in September.

“It was a great opportunity to meet industry experts and tell people about our work,” he said. “The next step is to get the brick into commercial production, which we hope to do by the end of the year.”

Dr Kandan added: “It is fantastic to see one of our own PhD students taking the lead on this project and sharing our results on an international platform.

“There is a constant drive for energy efficient building materials so it is very exciting to know that our brick can outperform the thermal insulation of standard building materials by an order of magnitude.”