How to grind concrete floors

using a concrete grinder

How to grind concrete floors

We’ll show you how to grind concrete in this post. There are many reasons to grind concrete. For repairs, renovating concrete and for decorative purposes. Concrete can be ground to a polished finish for decorative and maintenance reasons or ground roughly to make a better key for renovating your concrete.

See our renovating concrete post here!

Types of concrete

There are 2 types of concrete for grinding, new and old concrete. Grinding new concrete is best done by professionals and in consultation with your concreting professional and concrete supplier.

The new concrete should have properties that will deliver the best results for grinding. Plus you can add specific stones or objects and colors to your new concrete to enhance the ground concrete.

Old concrete will be a bit of a Pandora’s box, not knowing what will be revealed by grinding the concrete. You may not be able to get a polished finish on old concrete, but the blemishes and other issues will add character to the finished job.

Concrete grinders can be used either wet or dry depending on the results desired.

A dust removal system plus PPE should always be used when grinding concrete using the dry method.

Types of grinders

There are several types of concrete grinders available, from hand held grinders to large planetary grinders.

planetary concrete grinder
planetary concrete grinder

For general grinding a terrazzo grinder or a single cup grinder will do a decent job. Larger planetary grinders are used by professionals for large jobs with better results. To get the edges and corners of concrete slab ground down, hand held grinders may be used.

single disk concrete grinder
single disk concrete grinder

All concrete grinders use diamond cutting disks or wheels. To get a polished finish the diamond wheels or disks are range from coarse to very fine for the final passes.

The grade of diamond cutting disks used need to match the type of concrete being ground. For hard concrete you need a soft compound for the diamonds and for soft concrete you need a hard compound for the diamonds. If your not sure if your concrete is hard or soft, you can test it. Another way of determining if your concrete is hard or soft is to assess the concrete when you start to grind it. If the grinder isn’t doing much to the surface you probably have the wrong diamond compound for for grinding diamonds.

Using a concrete grinder

For the DIYer using a single cup concrete grinder is much like using a floor polisher. However when starting a concrete grinder always lift the grinding disk of the ground and lower onto the surface once it is started. Then grind in a sideways back and forth motion and pull back as you grind, never leave the grinder going in one spot.

To get an even surface may require that you grind one way and then at a 90 degree angle to the first pass. You will only achieve a coarse finish with a single disk grinder. These grinders are good for grinding concrete that is going to be resurfaced.

Always turn on your dust extraction system before starting your grinder if you are dry grinding. You may have to empty your dust extractor several times when grinding concrete.

Unless your grinder will grind up against the walls or edge of your concrete, you will need to use a hand grinder to finish the edges.

Dust extraction

Your dust extraction system can range from a shop vac to a dedicated dust extraction system. For small jobs a shop vac will suffice, use of a separator will help save your shop vac from an early death when concrete grinding. A professional dust extraction system will set you back a couple of thousand dollars, so unless your going into the concrete grinding business you won’t be needing this.

concrete grinding

Clean up

You will need to clean up your concrete surface after grinding to remove any dust or debris. Vacuum up as much dust as possible and then mop several times to remove any fine dust left from vacuuming.

If you use the wet grinding method , you will need to mop up the slurry and then re mop several times to remove all slurry produce when grinding.

After cleaning up you may need to repair parts of your concrete before you proceed to the next step of your concrete grinding project. Fill any cracks or holes and re grind these areas to match the surrounding surface.

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Finishing ground concrete

There are several options to finish your concrete grind project. You can resurface the concrete with a thin layer of resurfacing compound, or use concrete sealer to put a clear wet look on your concrete. Or you can keep grinding using finer and finer grade diamonds for a polished finish.

How you finish your concrete depends on what type of surface you want and whether the concrete is in the elements outdoors or under cover. Some finishes are not UV stable and are only suitable for interior use.

Looking at these options on how to grind concrete should help you determine if you are capable of grinding your own concrete or not. Small areas such as garages are good size grinding projects for DIYers, anything bigger should be given to professionals to complete.

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How to renovate your concrete

resurfaced concrete

Renovate your concrete

We’ll show you how to renovate your concrete surfaces in this post.

Have you a old driveway or patio that has seen better days. There are many ways to rejuvenate your concrete. You can repair, resurface and or replace your concrete depending on how badly it has deteriorated.

Inspect and assess

The first step in renovating your concrete is the inspect and assess your current concrete.

It may be cracked or worn, maybe discolored or you just want to freshen the concrete up.

If your concrete is badly cracked, it may be more economical to rip the old concrete out and replace with new concrete. For concrete that has the usual cracks that all concrete develops, there are products that will repair the cracks.

Your concrete may have been resurfaced originally and needs a spruce up. Or someone might have painted the concrete and it has started to flake. There are several methods to renovate these types of issues with your concrete.

After inspecting and assessing your concrete, you need to assess your skills. Are you capable of carrying out the repairs or processes required to reach your desired results. Your better to work this out before you start than finding out part way through that you can’t achieve the result your after. Some tasks are quite easy, such as sealing concrete but if you need to replace concrete it will be better to get a professional in to get the job done.

Repairing concrete

Repairing cracked concrete is one of the most common issues with concrete. The size of the crack determines the process required to repair the crack.

Hairline cracks up to a 1-2 mm can easily be repaired with a slurry of neat cement or a chalking filler. However the repaired cracks will stand out because of the difference in color to the old concrete. Coating or resurfacing the repaired concrete is the only way to have a uniform color of the concrete.

Large cracks

Larger cracks need to be assessed to determine if there is any movement still in the concrete or not. If there is no evidence of movement, gouge out the crack with a crack chaser or concrete saw. This will enlarge the crack and allow you a better key for your repair material. Remove any loose concrete and dirt from your crack and make sure the crack is dry before filling the crack. Mix up your repair material and trowel it into the crack, removing any air pockets by stabbing your trowel into the crack. Leave the filling material a little proud of the surface, so you can grind the repaired crack level with the surrounding concrete.

Where concrete with movement has cracks, you will need to fix the cause of the movement and then stitch the crack with metal and epoxy resign. Once you have stabilized the concrete you chase the crack out as explain in the previous paragraph. Removal of all debris from the crack with air pressure will also help dry out the crack. While chasing out the crack, you need to cut cross slots over the crack to allow for steel wire or rod to be in bedded into the epoxy resign. Place the steel in the cross cuts and mix up the epoxy filler to fill the cracks. Again leave the filler a little proud of the concrete surface to enable the crack repair to be ground level with the old concrete.

Chipped concrete

For chipped out concrete on edges you may need to place some boxing around to fill in the chipped out piece. Fixing chipped out concrete may require you to chisel out a little more concrete to get a better key. Mix up your concrete and lay it in the usual way, using your trowel, float and egder.

Painted concrete

Never paint your concrete! If you have painted concrete, you will know it is dangerous when wet and it will always peel.

Renovating painted concrete requires a concrete grinder to remove the paint. A grinder will remove a few millimetres of the concrete surface and allow you to resurface the concrete with a good key.

Concrete grinders work much the same way as a floor polisher works, only much more abrasive.

Check out our post on grinding concrete!

Colored concrete

Concrete can be colored in different ways, oxide may be thrown on once the concrete is laid. Or oxide made be added to the concrete when it is batched at the concrete plant. the concrete may be colored with a colored concrete sealer.

These can be renovated with out having to grind the surface. Usually a mild acid wash will give a good key for renovating colored concrete.

Thrown on oxide is only troweled into wet concrete and only goes down a millimetre or two, but chipped out concrete will be grey. Oxide added at the concrete plant will color the concrete all the way through, so any chip out will still be the same color as the rest of the concrete.

Sealed concrete needs to be maintained to remain in good condition. Most concrete sealers are not UV stable, meaning they deteriorate in sunlight, and will be eaten away over the years.

Resurfaced concrete

Resurfaced concrete can incorporate designs and multi colors. Concrete resurfacing adds a thin layer of concrete which is usually stronger than the concrete slab it covers. There are many stencils and colors available for resurfacing concrete.

If you are happy with your resurfaced concrete but it is looking a bit drab, resealing may be enough to make your resurfaced concrete look like new.

Exposed concrete

Renovating exposed concrete is one of the hardest things to do. Due to the stones being exposed and weathering over the years plus the fact that the stones vary in color from year to year, repairing exposed concrete is never going to look good.

If you want to stay with exposed concrete, you are best to cut out and replace whole sections. They will not match but will be better than blotchy patches.

Sealed concrete

Another option to rejuvenate your concrete is to use a concrete sealer. You can use the concrete sealer as a clear coat or add a tint to color your concrete. Sealing your concrete is relatively easy if your concrete is in reasonably good condition. There are many tint colors available for concrete sealers.

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Which option should you choose to renovate your concrete

The condition of your concrete is the major factor in which option you should choose when renovating your concrete. If your concrete is reasonable to good condition, you can choose any of the options discussed in this post. For concrete in poor condition, you are better off getting a professional in to complete the project.

Sealing concrete is the easiest and cheapest option to renovate concrete as you don’t require many tools and it’s pretty much the same as painting anything.

Resurfacing concrete requires a fair bit of experience and special tools, probably best left to the professionals.

Unless your concreting job is small, your better off getting professionals in as they have the resources and knowledge to do the job best. Small slabs up to a 1m square can be easily done by a DIYer in a weekend.

This will help you to renovate your concrete.

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How to choose a pressure washer

Pressure washer

How to choose a pressure washer? We’ll show you which pressure washer is best for your job.

What is a pressure washer?

Pressure washers pumps water at an increased pressure and speed of water to clean many different surfaces. A typical pressure washer will deliver 50% more power and use 80% less water than a garden hose.

Water blasters can be electrical or petrol powered, and deliver cold or hot water. Most pressure washers come with accessories such as different nozzles, brushes and detergent pickups.

Water blasters are measured by their PSI (pounds per square inch).

1000 – 4000 PSI pressure washers are good for general domestic jobs. Such as washing cars or decks and washing down siding. Washers in this range are usually electrically powered. Being electrically powered means that you are restricted to places with electricity and the length of your electrical cord.

The next step up in power is around 2500 – 4000 PSI. To get this sort of power the washers are powered by petrol engines. Petrol powered pressure washers are much more versatile than electric models. With petrol engine washers you are able to use them almost anywhere.

Bigger and more powerful pressure washers are over 4000 PSI. Some of these models can also produce hot water to clean tougher stains and chemicals. Models over 4000 PSI are used by professionals for commercial cleaning jobs.

Stanley pressure washer

Which pressure washer is best for you?

Questions to ask yourself are:

How often will you use a pressure washer?  If your only going to use your pressure washer on the odd occasion, maybe hiring a pressure cleaner is your best option. You may want to regularly clean your car or a outdoor deck. Then a electrical powered pressure washer could be the best model for you. Are you going to be using your pressure washer on a daily or weekly basis. A petrol model will be the model for you as these are more suited to commercial applications.

How big a job do you want use the pressure washer for?  The size of the area or job will also help you determine which model is best for you. If your only going to clean your car or have a small deck area, a electrical 1000 – 2000 PSI model would be suitable. Petrol powered washers are better for large jobs such as driveways and trucks and tractors.

What is it that you are trying to clean?   Electrical pressure washers for backyard decks or patios and cars.  For ground in dirt or oily stains a petrol power washer is the way to go. Commercial cleaners will often have pressure washers that heat the water to around 90 degrees Celsius to clean difficult stains without using harsh chemicals.

Do you have access to electricity and water?   Access to water and electricity allows you to use a electrical pressure washer, but this doesn’t mean you can’t use a petrol powered washer. If the area that needs to be cleaned is out of reach of your power cord and or hose, use a petrol powered washer.

RECOMMENDED PSI FOR APPLICATIONS

What’s the difference between PSI and GPM?

PSI is the pounds per square inch of pressure a washer puts out and is the usual method of rating pressure washers. Another measurement that helps determine the power of a pressure washer is GPM which stands for gallons of water used per minute. You get a deeper clean from a pressure washer with higher pressure and more water. Hence the best all round pressure cleaner has a high pressure output and uses more gallons per minute.

For example, you have a large driveway to clean. Using a pressure washer with a high PSI but low GPM will take a lot longer than using a high PSI and high GPM. A pressure washer with 3000 PSI and 4 GPM would be the ideal washer to clean your average driveway.

The PSI is what gets the dirt and grime off your surface, GPM is what washes the grime away.

Accessories

Most pressure washers come with accessories such as different nozzles, brushes and scrubbers.

Interchangable nozzles allow you to apply different amount of pressure to your cleaning surface. Red and yellow nozzles are hard and fast cleaning. Green nozzles are not as hard and white nozzles offer the widest spray. Black nozzles are generally for applying detergent and very light pressure. Turbo nozzles operate in a spinning fashion and increase the cleaning efficiency.

PRESSURE WASHER NOZZLES

Brushes are good for washing your car and usually have a spinning action.

Scrubbers are for cleaning large flat surfaces, such as decks, driveways and roofs.

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Pressure washer safety

Pressure washers exert high forces when in operation. Always use two hands, don’t point the lance at people or animals. Test surfaces to determine pressure required for the job. Don’t blast electrical wires or power points. Keep the nozzle moving to avoid cutting into the surface. Take extra precautions when using a ladder or on a roof.

Don’t use petrol or diesel powered pressure washers in enclosed areas.

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Which pressure washer should you choose?

If you only have small, lightly soiled surfaces around the home, a electric pressure washer is for you. These are light and easy to handle.

You need a petrol powered pressure washer for your larger jobs. The PSI and GPM will depend on the type of jobs you want to carry out.

If you are going into the pressure washing business, you’ll need an industrial model.

I hope this has helped you choose a pressure washer for your specific needs.

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