A Road To A Better Life
Energy and Change
Caden Sides
- Grade:
- 7
- Teacher:
- Lee Ann Howell
The purpose of this experiment was to evaluate whether recycled plastic could partially replace gravel in concrete to produce a lighter material without significantly reducing strength. This investigation explored the potential of plastic-infused concrete for road construction. The independent variable was the amount of recycled plastic added to the concrete mixture, while the dependent variable was the maximum weight each concrete brick could support. The hypothesis stated that if recycled plastic, an abundant material, replaced a portion of gravel in concrete, then the resulting material would be durable while also being more environmentally sustainable.
You chose a real-world engineering problem — reducing plastic waste while improving building materials — and that shows creativity, environmental awareness, and advanced scientific thinking.
Your research question was clear: Can recycled plastic partially replace gravel in concrete to make it lighter without significantly reducing its strength? That is exactly how engineers think — balancing weight, cost, sustainability, and structural strength.
Even though your results did not support your hypothesis, this does not mean your experiment failed. In fact, this is what real science looks like. Many scientific breakthroughs begin with a hypothesis that turns out to be incorrect. What matters most is that you tested your idea carefully and honestly reported the results.
Your results likely showed that while adding recycled plastic made the concrete lighter, it reduced compressive strength more than expected. This makes sense scientifically because gravel (aggregate) provides strong structural support in concrete. Plastic is lighter and less rigid, so it may not bond as strongly with cement.
What is especially impressive is that you were able to evaluate trade-offs. Engineering is often about compromise. Sometimes making something lighter reduces strength. Your experiment helped demonstrate that balance.
Most importantly, you showed resilience. Science is not about proving yourself right — it is about discovering the truth. By reporting that your hypothesis was not supported, you demonstrated honesty, maturity, and real scientific integrity.
This is the kind of thinking that leads to future engineers and innovators. You should be very proud of your work.