While at university, Singaporean chemical engineering student and 2014 Bayer Youth Environmental Leader Kevin Lee decided to experiment with developing green materials. Now he’s developed a cement composite that incorporates horticultural and wood waste – an innovative way to make good use of stuff that would otherwise be incinerated or sent to landfill. TUNZA talked to Kevin …
Tell us about your composite – what are you doing?
I’m developing ways to recycle wood and horticultural waste into a greener concrete. In a nutshell, I replace imported sand and gravel found in Singapore’s traditional concrete composites with horticultural waste, creating an alternative while recycling wastes and lowering the carbon footprint of building materials.
How much waste is there in Singapore – isn’t this material already recycled?
About 345,000 tonnes of wood waste and nearly 250,000 tonnes of horticultural waste were generated in Singapore last year. Some of it is recycled into compost or charcoal, but the recycling rate is pretty low and inefficient – plus recycling methods are energy and carbon intensive. Horticultural waste also goes to landfill. Singapore is small, and has major land constraints. If we could divert waste from landfill, we’d save space for housing, parks, and so on.
As for the rest, 500 tonnes of wood and horticultural waste are still incinerated every day – wasting material and causing air pollution. So I thought, what can we do to increase the rate of recycling, and reduce incineration?
It’s kind of hard to believe, but to date there is no viable technology in the world that allows us to recycle wood and agricultural wastes into buildling materials. I hope to change that.
What did you decide to do?
In my research, I found that the cement and concrete industry consumes nearly 2.77 billion tons of cement annually, translating to global carbon emissions of 2.07 billion tonnes a year. So I thought, “What if we use horticultural waste to help make these building materials less carbon intensive?” I developed a cementitious composite using recycled wood and horticultural waste as a partial replacement for sand and gravel.
I treated the wood, worked out the correct sizes of particle required for sand and gravel replacement, and tried mixing many formulations – 26 in total! – before I found the perfect one based on strength, water absorption and density. I went on to develop molds so that I could use the new composite to cast objects. We’ve used our composite to create beautiful park benches, stylish outdoor furniture, water features to be used in landscaping, and so on. The material can also be used to make kerbstones, beams, and paving slabs, and more. All the possibilities have yet to be explored.
I also spent lots of time doing outreach, helping the public understand how wood and horticulture waste can be recycled, and how their choices can help mitigate climate change. I enlisted students to help me collect wood and horticultural waste, and more than 600 young people have pledged their commitment to recycling.
Do you think you can expand this project?
I’d like to pilot this concept in countries with agricultural industries that produce even more horticultural waste than Singapore. In Indonesia, for example, plantation owners adopt the slash-and-burn technique to clear land, wasting a huge potential resource. I also hope to educate and raise awareness of global warming to farmers, plantation owners and villagers in countries surrounding Singapore.
You studied wastewater treatment, not green materials. Had you envisioned this as part of your future?
I hadn’t planned to take this particular path. But now, with my experience and the knowledge I’ve gained about current pressing environmental issues, I feel motivated to carry on with this project. I believe my work will play a part in tomorrow’s world.