Q: I just read your column on staining concrete driveways. I have a similar problem, but my driveway is blacktop. I have a 60-year-old, red-brick home. The mortar was cracking and eroding between some of the bricks. I was advised to "point them up" with new mortar.
The contractor was sloppy with the mortar and it not only dribbled down the side of the house, but also splattered along the driveway. Do you have any ideas on how I can clean up the bricks and the driveway?
A: Not to beat you up, but did you inspect the job before you paid the guy? Our guess is either you didn’t do a final inspection or you simply overlooked the sloppiness of the finished product. Either way, the simple matter of washing the brick and hosing down the driveway has morphed into a much bigger job.
Mortar is easy to remove from brick when it’s fresh. But in about a month the Portland cement cures and cleanup becomes a lot tougher. The good news is you can remove the stains on the brick and cover the splatter on the driveway with some elbow grease, some time, some asphalt coating and an acid.
Let’s start with the brick. Try a grout cleaner first. If the mortar splatters aren’t too bad, this may do the trick. Most masonry and grout cleaners on the market contain phosphoric acid. It’s safer than its commercial cousin, muriatic acid.
A good mason gives his brickwork a cleaning with muriatic acid as the final step of the job. Phosphoric acid masonry cleaner may be adequate if the staining is not too severe. If you need to pull out the big gun, muriatic acid is the ticket.
Always use muriatic acid in solution. The standard dilution for most applications is 1 part muriatic acid to 10 parts water. Use a plastic bucket to mix the concoction. Glass is OK, but obviously it can break. Do not use metal or ceramic vessels, as they cause a reaction producing noxious fumes.
Brush the stains on the brick with a wire brush to remove any loose mortar. Then apply the acid mixture with a large sponge. Leave the acid in contact with the masonry for 30 seconds or so. New stains will release almost instantly. Older ones like yours will take some time. Brushing with a softer scrub brush might help.
Have a bucket of water or a garden hose ready to rinse off the acid. Reapply the acid solution as necessary until staining disappears. When you’re satisfied, rinse thoroughly with water and neutralize the cleaned area with 1 cup of household ammonia to 1 gallon of water. Finally, do a thorough rinse with water.
Cleaning could be a long process, so we suggest you do the job in manageable sections.
Muriatic acid is dangerous. Contact with the eyes can cause irreversible damage and permanent blindness. Contact with the skin can cause severe burns. If you get any on you, immediately flush the area with water.
Follow these precautions:
- Dress appropriately. Wear gauntlet-style acid-resistant gloves, the kind that go halfway up the arm. Wear goggle-type eye protection. A respirator equipped with an acid-grade filter is also a good idea if ventilation is questionable.
- Have a neutralizing agent and a reliable, steady source of water available. Baking soda or garden lime can quickly neutralize the acid if spilled. Have a garden hose handy to flush any contact with eyes or skin.
- Because muriatic acid can damage or kill foliage, cover or wet all nearby foliage with water before applying the acid. If the foliage has been accidentally doused with acid, a neutralizing mix of lime and water can be applied to the plant and/or soil.
- Adequate ventilation is a must. Muriatic acid is nonflammable, but the vapors are highly corrosive and irritating.
- Dispose of the leftover acid solution by neutralizing it with lime or baking soda. Don’t dump it down a drain or flush it down the toilet. Use a 5-gallon plastic bucket to minimize splattering. Put 3 or 4 cups of lime or baking soda in the bottom and mix in a gallon of water. Slowly add the leftover acid to the bucket, keeping your face away while pouring. The mixture will fizz. It will also produce chlorine gas, so it would be a good idea to wear your respirator or a surgical mask. Mix it and stir in more lime until all chemical "fizzing" has stopped. The fully neutralized acid can now be safely disposed down a sink or storm drain without fear of damage to the environment.
Comparatively speaking, taking care of the asphalt driveway is easy. Sweep the spotted areas with a stiff broom, thoroughly hose down the entire driveway to get rid of dirt and mortar residue, and let it dry.
Then roll on a topcoat of asphalt sealer, available at any hardware store or home center. In addition to covering the mortar spots, the sealer will fill any cracks that may have developed in the driveway.
We’re sorry you have to go to all this trouble to fix the contractor’s laziness. We guess the moral of this story is to do a thorough inspection of the "completed" job before paying for it.
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