How do I remove concrete from a concrete mixer? This is a question, which is important for the maintenance of concrete mixers. For the old cement on the mixer: Begin by turning on the mixer and allowing it to spin. Add a couple of gallons of water to the mixer. While it is spinning, gently tap the outside of the drum with a rubber mallet or small hammer. Use caution not to make big dents on the drum. As you are hitting the outside of the drum, the cement should begin to break up and fall off the wall. After the large chunks are removed, open the release and allow the water and chunks of cement to drain out. Use a chisel to knock off any remaining chunks from the surface. Next, put on your protective gloves and goggles. To remove the final layer of cement, pour one part hydrochloric acid into two parts water in a bucket. Always pour the acid into the water, and not the other way around! Add the acid mixture to the barrel and keep it spinning. The acid will remove the final layers of cement from the surface. Tilt the mixer so that the acid/water mixture reaches all the way to the edges of the barrel. Once the cement is removed, drain and dispose of the acid appropriately. Rinse the drum out completely with water. A hose or pressure washer is useful for this. Allow the mixer to dry before storing. Ways to clean the wet cement on the mixer: Once a cement mixer is properly cleaned, it is easy to maintain. The key is to clean it promptly after each use. Use a hose to fill the mixer with 3-4 gallons of water. Add in a couple shovels full of crushed rock. Turn the mixer on and allow it to spin. The gravel will move with the water and scrape the cement off of the sides. Tilt the machine to clean all the way to the edges. Once the cement has been removed, drain the water and gravel. If the mixer is used frequently, it may be helpful to build a small “cleaning station.” Fill an area larger than your mixer with at least a half a foot of gravel with crushed rock on top. When you are finished cleaning, simply drain the mixer right onto the same area. The cement water will drain to the bottom, while the rock stays clean on top. Simply scoop from the area each time. This provides an easy area for cleaning as well as allows you to reuse the crushed rock. Use a hose or pressure washer to remove any remaining residue from the interior and exterior of the machine. Dry the machine prior to storing. Additional Tips and Advice If you need to scrub the surface of the mixer, a stiff toilet brush works well. Crete-lease is a lubricant that can be applied to the exterior of the mixer. It will prevent the cement from sticking to the surface. A light coating of diesel fuel can be used on the inside of the drum to keep the cement from sticking to the inside. Use it sparingly as diesel fuel can break down the cement and ruin it. Pressure washers offer another alternative to chemicals. Though they may not be able to remove all of the cement that has cured, it works great for cleaning out wet cement. Always add the acid to the water, not vice versa. Always remember safety first in all the work.