This is intended for use with Polymer Resin sealers or Solution Acrylic sealers with the intention of achieving a high gloss or satin finish. There are many reputable concrete sealers on the market and it is advisable to check their MSDS and TDS documents prior to use. Different types of concrete paving require different preparation and sealing procedures. The following guidelines are suggestions only, and specific manufacturer’s recommendations should always be carefully regarded. If I was to recommend one, well that would be the product I have used for some time now and that’s “Nutech”. It has proven to be consistent and their technical department have assisted me very well, on the odd occasion, when that difficult question arises.
Sealing a driveway helps to protect it from the weather, road salt and other stains that commonly occur on surfaces underneath vehicles. Oil, dirt and grease are common stains on driveways. Sealing a driveway also protects it from wear and tear, which helps to reduce the costs associated with having to replace it. Use these tips to reseal your driveway.
Make sure you keep safety in mind for yourself and others.
- Read the MSDS and TDS for all chemical that you are working with and comply with their recommendations
- Read and understand operational instruction for all equipment being used. This is often missed when borrowing from a friend.
1 Clean and prepare the drive for resealing
- Treating stains on the driveway can be simple. First grab a few cups of laundry powder and sprinkle over the stained area and lightly spray with the hose or watering can. Allow this to sit for a little while and penetrate the stain, then give some agitation with a long handle deck scrub. Do Not do this on your hands and knees and keep your face well away from the working area. Hose the area of and then mix a 2-3% solution of hydrochloric acid, 1 part acid to 10-15 parts water. Pour this over the residual stain using a watering can and let rest for five minutes. This has a dual application, one being final cosmetic cleaning and the other is etching; in particular smooth finished concrete for porosity and high adhesion.
- Pressure clean your driveway, using a 3000-4000 psi pressure washer. Be careful and check that the tip is a small fan and not a streamline jet as this will blast your concrete away. Hold the gun about 150mm (6”) from the drive, cleaning the entire area. You will need some patients, as this takes considerable time. If there are still stains, you may need to repeat the cleaning process.
- Fill in minor cracks or chips with a driveway patch; this is easily achieved by crushing a small portion of your drive or a small piece from an adjoining footpath into a dust, then mixing this fine dust/powder with Bondcrete until it has a consistency of toothpaste then push into the chip or crack. This will dry hard in about an hour; working time is about 15 minutes.
2 Let the pressure-washed driveway completely dry
- Your drive needs to be completely dry. Here’s a tip, if you have a blower (petrol broom) use this to get the residual water out of the cracks. In the warmer months your driveway, in full sun, will take a couple of hours to dry.
- This is a visual inspection, if you see darker spots, and in particular along the control joints, your driveway is still holding moisture and considered to be wet.
- At this point the cost of this project should be fairly minimal, but it is important you have done this wright.
3 Select and prepare your sealer
- Let’s check the weather and see that your chosen sealer falls within its parameters and application guidelines. The main thing here is ambient temperature and or rain.
- This can be generally purchased from a good hardware store or better yet a masonry supplier. If you are applying a 2 coat system, then I would recommend that the first coat is mixed with thinners (xylene) for a penetrating initial coat.
- If you don’t already know the square meterage of your area then it’s time to calculate this on a length by width basis.
4 Cut in and First Coat
- Tape up surfaces where you don’t want any sealer, as it is not easily removed.
- Mix your base coat as per TDS, but as a guideline it should be mixed with 10-50% thinners for penetration into porous surfaces (first coat only). 1ltr should cover between 4-5m2.
- Grab an old paint brush or a cheap new one, then begin cutting in around downpipes and etc., bearing in mind that most areas, your sealer can be applied with a roller.
- Handy tip – take it slow and easy near structure or windows, I have seen roller spray well over one meter up a wall, garage door and windows.
5 Second coat
- First coat is typically touch dry in an hour after application in the warmer months.
- The second coat should be applied neat unless the weather is quite warm, this being the case, the second coat should be thinned by 10%. This can reduce surface bubbling and you should expect that a coverage of 4 square meters per litre.
- If you have smooth concrete in a wet area that gets slippery, now is the time to add an anti-slip additive. Fine particles are for moderate slip resistance and larger particle powders are for sloping surfaces.
6 Other tips
- Allow at least several days to harden before driving is allowed, and even longer in cold weather. You can generally walk on your sealed pavement hours after application if you have to, but keep it to a minimum.
- I often get asked why my driveway is patchy. In the first instance, it is the sealer curing and this can take up to one month to settle right down
- Inadequate surface preparation is the main cause for sealer failure. The use of a fire hose or nozzle attachment to a garden hose does not replace a pressure cleaner.
- Existing sealers may not react with a solvent based thinner, thus requiring a release agent to chemically strip the old sealer.
o Test a small area and observe for a few weeks.
- Delamination has occurred; this could be that the original application did not penetrate into the concrete. Acid etching can assist, but if delamination persists in 3-6 weeks you need to use a seal repair solution which penetrates the original sealer by melting and repairing all coats.
o This is a very grey area to actually pin point what may have caused any delamination, even a very experienced tradie will struggle.
That’s it for this edition, if you have any ideas please get in touch with us at WCC
Our next Trade Secrets article is going to be – “Things to look out for when starting a project”
- Existing services
- Local authorities
This is intended for use with Polymer Resin sealers or Solution Acrylic sealers with the intention of achieving a high gloss or satin finish.