A cubic yard of concrete will require several bags. The number of bags required depends on the type of concrete mix you use for your project. If you're using 50-pound bags of concrete, you'll need 72 of them to fill a yard. You'll need 60 60-lb bags of concrete to construct a yard if you're using 60-lb bags. Concrete is heavy, so you should use a scale to measure out your ingredients accurately. Concrete is heavy, water is light, so start by weighing the cement bag to ensure that you get an equal amount in each bag. Next, weigh the aggregate (sand or stone) and divide it by the number of bags needed to reach the desired weight. For example, if you want the concrete to be half its original weight after drying, add half as much sand as cement. Now you can mix up the concrete. First, pour all the water into the mixer until it's fully submerged under water. Add the cement and mix on low speed for about 30 seconds, then increase the mixer speed and mix for another 30 seconds. The purpose of this step is to distribute the cement powder evenly throughout the water. After mixing the concrete, pour it into the forms you've prepared on top of the gravel base. Level the surface with a float or shovel and let the concrete dry for at least 24 hours before moving it into the sun. Drying time may be longer depending on the weather.