How to Remove Oil from Paving: Fresh Spills and Old Stains

Fresh oil: contain it, then absorb it

The Concrete Institute says oil stains can be extremely difficult to remove from concrete because of their rapid ingress into the concrete. The CMA notes that concrete block paving itself is not affected by oil stains; the problem is the mark.

1. Ring the spill with a fine, dry material such as sand, cement, sawdust or cat litter, so the stain cannot spread (The Concrete Institute).
2. Mop up as much as possible with paper towels or cloths, blotting rather than wiping, then sprinkle the whole stain generously with the fine material, broom it back and forth, sweep it up and dispose of it (The Concrete Institute).
3. For oil that has penetrated, the CMHA paving guideline says to cover the area with an oil absorbent such as kitty litter, and lists talc, fuller's earth and diatomaceous earth as alternatives. It says to leave it on the stain for a day, then sweep up.

Kärcher's South African guide gives a similar household answer: where no special cleaner is to hand, it uses cat litter or sawdust to soak up the oil, then sweeps it away.

How to remove oil from paving once it has set

The Concrete Institute says a stiff bristle brush is useful for thick surface oil deposits but inadequate for deposits that have already penetrated into the pores of the concrete. It has found three cleaners that work on oil stains: car engine degreaser, high-foam washing powder and concentrated liquid detergent.

The CMA's design manual says there are proprietary products designed specifically for removing oil stains from block paving. Where these are not available, it recommends scrubbing the paving with a strong detergent.

Before any of these, The Concrete Institute says to treat a small trial area in an inconspicuous place, to see the effect the cleaning method will have on the concrete. The CMHA guideline adds that deep-set oil stains often require repeated applications of the remover.

Clay pavers need different handling

De Hoop Steenwerwe, a clay brick maker, writes about clay pavers separately. It says oil does not soak readily into clay pavers, and that a spill should be lifted promptly with something absorbent, such as paper towels. It says the oil should not be wiped up, because that spreads the contamination on the surface of the paver. If its first cleaning method is unsuccessful, it says an emulsifying de-greaser should be employed.

For specific cleaning situations like oil stains, De Hoop suggests commercial cleaners available at masonry supply outlets, and says to always test any cleaner on a small hidden portion of the pavement first. It says pressure washers are not recommended on flexible base applications, because they tend to remove joint sand, which compromises interlock.

Sealing against oil: the bodies disagree

The CMHA guideline says sealers reduce the intrusion of stains, oils and dirt into the paver surface. The CMA's homeowner guide lists surface sealants as not recommended on block paving, citing high initial cost, abrasion that removes the sealer and regular maintenance.

For paving cleaning in Cape Town, the mean of three Cape Town cleaners' published prices is about R45 per m². Paving for Africa cleans and seals paving. Weeds and green growth have their own guides, on weeds between pavers and on moss and algae on paving.

Oil stain questions