Concrete is a mixture of plain cement, water, some air and aggregate. Traditional types of aggregate include gravel and sand, but many people use recycled materials, such as broken glass, in their place. Mixing concrete using recycled broken glass as aggregate not only produces a strong and distinctive concrete, but also keeps that glass out of landfills. When choosing the type of crushed glass, consider whether people will touch or walk on the concrete. Plain broken glass, called cullet, is fine for surfaces that will never touch skin, but smooth tumbled glass is preferable for other surfaces.
Empty the glass into a large container. Rinse the glass well with plain water and move it from the water to a large, flat surface. Let the glass dry overnight.
Choose a concrete mixer suited to the size of your job and connect it to a power source. Fill the barrel of the mixer with two parts plain Portland cement to three parts glass aggregate. Add one part water and turn on the barrel.
Allow the barrel to rotate between 50 and 75 times; this adds air to the concrete in addition to mixing it to an even consistency. If the concrete seems dry, add more water a little at a time until the texture is like thick cake batter. Use the prepared concrete as you wish.