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Jim asked: How do I remove concrete from a concrete mixer? I purchased a lightly used and old, heavy duty, metal concrete mixer with splashes, spills and washes of concrete over 75% of the machine. I want to remove the concrete without denting it up or damaging the paint. Do you have a homemade solution I could mix up to be sprayed on to aid in removing the concrete, besides purchasing an expensive chemical to do it? I appreciate your help.
When it comes to removing old, dried on cement, there are few options. It either has to be chiseled or knocked off, or eaten away with acid. However, once the old cement is removed, it can be easily maintained without the labor intensive cleaning methods or chemicals.
Removing Old, Dried-On Cement
You Will Need:
- Hydrochloric acid or Muriatic acid
- Chisel
- Hammer or Rubber mallet
- Water
- Protective goggles and gloves
- Bucket
Steps to Remove the Old Cement:
- 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.
Cleaning Away Fresh, Wet Cement
You Will Need:
- Water (a hose is helpful)
- Crushed rock or hydro rock (3/4” is recommended)
- Pressure washer (optional)
- Shovel
Steps to Clean Wet Cement:
- 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.
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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.
If you are running a mixer or concrete truck for a living, it is always smart to carry several 5 lb. bags of sugar with you in the event that the concrete is blowing up in the drum, or you have mechanical failure.
In either case add water and a bag of sugar into the drum and it will prevent the concrete from setting up.
Will an air scaler remove the concrete without removing the paint on a cement mixer?
Spray the metal with diesel and let it soak. You may have to do it a couple of times; over time, it will get under the cement and lift it off.
Use a SDS drill on hammer only; the vibrations make the old, hardened concrete just fall off.
How do I remove concrete from a concrete mixer truck? My concrete mixer truck engine went off while running inside almost 7 qmtr. concrete. The concrete is already hard and I can’t remove it. I want to remove the concrete from my truck without denting it up or damaging the truck. Do you have a solution, besides purchasing an expensive chemical to do it? I appreciate your help.
Put a couple of rocks in it with some water.
Let it spin and as the rocks tumble, they will remove much of the hardened concrete.
Never use acid. It will only corrode the metal. A hot, high-pressure water blaster is your best bet. I have been using these things for 30 years and so far this has the best result.