A concrete mixer is a handy machine for mixing large batches of concrete. The mixer blade and drum should be cleaned immediately while the concrete is still wet; however, sometimes, this just isn't feasible. If the concrete dries onto the concrete mixer, it's harder to clean, but not impossible. Use the right products and methods to clean dried concrete off the mixer to ensure your safety while getting the machine clean.
Turn on the concrete mixer and let it spin a few times. Slowly pour 2 gallons of warm water into the mixer.
Tap the exterior of the mixing drum gently with a rubber mallet. Do this several times until the large chunks of concrete are removed. Be careful when hitting the drum so you don't make dents.
Open up the release and let the water, along with the chunks of cement, to drain. Take a chisel and gently pry off any chunks still remaining on the mixer.
Use hydrochloric acid if there is still concrete left on the mixer. Put on long, thick clothing and wear protective eye wear and thick work gloves.
Fill a bucket with two parts water and one part hydrochloric acid. Pour the water into the bucket first, and then the acid. Never pour the hydrochloric acid into the water.
Keep the mixer spinning and slowly pour in the acid and water mixture. If necessary, tilt the concrete mixer to the sides to allow the acid mixture to get onto the edges.
Drain the acid mixture once all of the cement has been removed. Check with your local hazardous waste disposal centre for instructions on disposing of hydrochloric acid. Different states and local governments have different requirements for disposing of hazardous materials.
Rinse out the interior drum and blades of the mixer thoroughly with water from the garden hose. Let the mixer dry completely before storing it.