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Remove oil stains from concrete

Grease and oil stains in concrete can be difficult to remove and we asked the Concrete Institute to offer a solution on how to remove oil stains from concrete.

 

Grease and oil stains on concrete driveways, in a garage with concrete floor, or parking areas, can be an eyesore. The Concrete Institute says that, although most common oil stains can be extremely difficult to remove because of their rapid ingress into the concrete, there is a solution. Here are some guidelines on how to deal with this problem.

Firstly, before attempting to remove any stain from concrete, an inconspicuous place should be treated first to assess the effect the cleaning method will have on the concrete. You don't want to put too much time and effort into removing stains that been absorbed deep into the concrete.

The most important action that can be taken is to stop the stain from spreading. To do this sprinkle any grease or oil stain with   a fine, dry material such as sand, sawdust or even cat litter. Mop up as much of the stain as possible with paper towels or cloths - blotting rather than wiping and then sprinkle the entire stain generously with the fine material. Use a soft broom to sweep this back and forth over the stain before removing.

The Concrete Institute recommends one of the following cleaning materials for removing oil stains:

  • Automotive engine degreasers
  • High-foam washing powder
  • Concentrated liquid detergent

GOOD TO KNOW:
These products are more effective when mixed and applied with boiling water. A stiff bristle brush, although useful for removing thick surface oil deposits, is inadequate for reaching deposits that have already penetrated into the pores of the concrete.

A high-pressure washer is also extremely effective in removing ingrained stains. The high pressure cleaner should be used  after the cleaning agent was applied but before it has evaporated. For this reason application of the cleaning agent in direct sunlight is not recommended.

As soon as the oil or grease deposit has been removed, the entire area should be flushed with copious amounts of clean water to prevent soiled water re-depositing the oil on adjacent concrete.

GOOD TO KNOW:
Be careful when using a high-pressure washer on concrete that is flaking or breaking up. Wear protective clothing and goggles to protect against the rebounding of grit when the high-pressure washer displaces material from the concrete or between block paving.

Once most of the surface stain has been removed, cover the residue with a poultice made up of one part agricultural lime* to two parts mineral turpentine. Spread a layer of about 5mm of the paste over the stained area, ensuring that there is a margin of approximately 50 to 100mm around the edges. Cover the plastic sheeting and leave for 24 hours. Builders’ lime should not be used as it could cause skin burns.

It may be necessary to repeat this process within a day or so to remove any deeply ingrained oil or grease that sometimes continues to rise to the surface. Finally, scrub the stained area with warm water and laundry detergent, then rinse well with clean water to end the treatment.

*You will find agricultural lime at Farm City, Town and Country, AFGRI, agricultural supply store and select garden centres.

 

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