Human Powered Concrete Mixer

For my senior year Capstone project I led a team of like-minded students to complete a project for Engineers without Borders and African Sky. Our project was undertaken to help African Sky’s efforts to expand education in Mali, Africa by building schools. The schools’ foundations and bond beams are composed of concrete. Their current method of mixing concrete, with shovels on the ground, is strenuous, environmentally unfriendly, and wasteful. We developed a design that was human-powered, cheap, transportable, efficient, ergonomic, and made out of available materials.

          As the leader, I was personally in charge of many of the responsibilities for the project. I researched, designed, modeled, made drawings, prototyped, built, analyzed, and tested the human-powered concrete mixer as well as made assembly and user manuals. I analyzed the steel pipe frame using FEA analysis to confirm that it could hold the required load of concrete and completed additional analysis on the bolted corner flanges to verify the robustness of the design. Also, I optimized the frame design and tarp dimensions to ensure that it was ergonomic and could efficiently mix the concrete. Furthermore, tensile tests were conducted on various tarp samples to ensure that the tarp could withstand the wear from mixing concrete. The completed design could mix three cubic feet of concrete in two minutes which is six times faster than the benchmark and has eight times less power requirement.  The design will be implemented in future projects by African Sky. To see it in action please watch this video.