UC Berkeley Construction class project required our own concrete mix formula, span 30", and weigh under 150 lbs. In the early stages of the project, we experimented with 8 different mixtures, including different aggregates to potentially lighten the weight of the project, and differing the proportions of sand , cement, and aggregate. With extreme attention to the reinforcement detail, our group had the lightest project (50 lbs), with the thinnest section (2") out of the 60 students in the class.