Recent RPI Masters of Architecture graduate Henry Miller has devised a way to reuse waste plastic as an aggregate in cement, circumventing the energy-intensive process of plastic recycling. By grinding up landfill-bound plastic and mixing it with portland cement, Miller was able to create a material just as strong as traditional concrete made with mined aggregate. The ingenious solution netted miller first place in the “Component Category” of the second annual Concrete Thinking for a Sustainable World competition.

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Using recycled materials is so hot right now, but using them as aggregate is hotter than Hansel in a black shirt on a summer Sunday. While living in Albany, Miller saw many areas cut their plastic recycling programs for the cheaper (now) solution of landfills, and noticed the astounding number of brownfield sites that were simply being abandoned. Miller’s idea: Why not use plastic waste as an aggregate in concrete and create a more sensible product. By mixing together ground-up plastic with cement and soil reclaimed from the brownfields, Miller was able to create a material just as strong as conventional concrete.

The Concrete Thinking for a Sustainable World competition only asked students to conceptualize a design, but Miller he was not satisfied with a mere idea. He actually used his plastic concrete to build a screen and a wall. In doing so he showed that his ideas were viable alternatives to the status quo and that there was no excuse to merely fall in line.

Describing his project, Henry Louis Miller states: “Recycling plastics is a difficult, energy intensive process, and yields a product that is inferior to the virgin material. I have researched the possibility of using granulated, post consumer waste plastics as the aggregate in concrete. In this application, unlike plastics can be universally mixed with no adverse affects, heat driven re-amalgamation is not required, and my early test results show the resulting product is as strong as conventional concrete mixes (between 3000 and 5000psi.) As a result of using plastic rather than conventional aggregate, the mining of new material to serve as aggregate is not necessary.”

+ Concrete Thinking for a Sustainable World Competition

+ RPI’s Masters of Architecture