Driveways, Walkways

Published on July 28th, 2015 | by Henri


Cleaning and sealing a concrete driveway

Q.    About 10 years ago, I had a concrete driveway put in. The company put a concrete sealer on the driveway, then told me it was saturated and needed no more treatment for a few years. Since then, the driveway has become stained with organic things (mold, crab apples, leaves, etc.) and non-organic things (black tires marks, etc.)

Last summer, I power-washed the driveway using a concrete and driveway cleaner with little in the way of results. Later, I accidentally spilled some chlorine bleach on one section of the driveway and it looked great.

Can I use a hand tank sprayer and spray a water/bleach solution on the rest of the driveway? Would it ruin the sealant? If not, what percentage water/bleach should I use? How often can I use this solution safely? Thank you for any help you can give me.

A.    The sealant applied was topical; it forms a film and needs to be re-applied every year or two. The other type of sealer is penetrating, which needs to be applied only once, as it seals the pores of the concrete.
Nature does a great job of cleaning concrete from organic matter stains, and of tire marks as well. Snow over the winter will bleach the concrete very effectively in your climate (Pennsylvania).

But if it doesn’t to your satisfaction, go ahead and spray the concrete with a mixture a water and bleach. Start with 1/3rd bleach to 2/3rd water, and increase the bleach proportion if it does not satisfactorily do the job. Once clean, rinse well with your garden hose or pressure washer.

Once clean, if you decide to apply a penetrating sealer, wet the concrete to see if water penetrates it or beads on its surface. If the water penetrates, a penetrating sealer should work.

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