Outdoor concrete repair/resurface/sealing and painting

[diogofcr]

We have an outdoor patio at my house which was made of concrete, but I don't think it ever got the finishing coat (it was supposed to be tiled but never happened) nor sealed and it has been there for 10 years or more.
The concrete is really damaged in some spots, we already knew that. Today we decided to power wash it so we removed the damaged concrete which was already only sand in some places, so we can later resurface and fix it.

Before power wash:

After power wash:

As you can see the concrete is really really damaged in some places. Here are some close-ups:

How can we repair the holes?

My plan was to use a concrete repairing compound on the holes like this one:

Would this be appropriate to repair the holes? Should I add some kind of glue around the concrete holes before filling it with the compound? (I saw some video of one guy doing this)

After the holes were repaired the plan would be to resurface the whole concrete. How could I do this and leave a smooth finish? I was thinking of using this product: (sorry it is in Portuguese)https://secilpro.com/upload/documents/5cd04d0e01b89.pdf

Would this work? If not what do you advise?

After resurfacing we wanted to seal it. Which sealant could I use? We wanted to paint over it if possible.
I read about a liquid membrane sealer but I also think that you can't paint over them, am I right?

Also the concrete is a bit slopped so the water flows to the center drain. Resurfacing wouldn't ruin this right? In my view the resurface compound would just follow along the profile of the pre-existing concrete. I guess I just **can't use self-leveling compound** or I would ruin this slope, right?

Thank you everyone for the help, looking forward for answers

 

[yetihunter]

Bump as I’m dealing with a lot of concrete repairs and my results are as you’d expect from a first-timer. 

 

[six-point socket II]

Hi!

Honestly, where to start?

That is quite substantial damage. This is not something that is fixed with filling some of the holes/ spot repair.

First you need to further asses the actual damage. I can see cracks that seem to run below the top surface. All of these cracks need to be found and opened. All loose material removed, thoroughly.

The pictures tell only one side of the story, the real question is if that concrete was mixed and poured correctly.

If done professionally, you'd use a "hole saw"/core drill and analyze the concrete. Then a specialist would set out an exact procedure on how to fix this and what material is to be used for that.

Let's say you removed all the loose stuff and all cracks lie open.

You'd start with a primer, not just any primer but a bonding agent/coupling agent/adhesive-promoting agent especially for concrete.

Once that has dried, you can fill the cracks and holes.

Whatever you use to fill the cracks and holes has to be suitable for the depth of the cracks/holes and corresponding needed layers of material. I don't know the products you have linked, but the "structural" part in the Name of that Axton product, makes me think you are on the right track. You definitely need a product that is suitable for structural concrete repairs.

There are also epoxy (resin + curing agent) products available to repair the cracks, not so much for the holes.

Then I'd suggest using a mesh material that you place all over the (now closed) cracks, you use the primer to get it to stick. It's a good idea to use primer on the whole surface now.

Then you can make a new top surface/layer. For keeping the slope you need a material that won't run like water. So yeah, the self-leveling stuff, I won't recommend it. You need something with thicker consistency.

Finally, I'd suggest using epoxy flooring to get a robust, water tight seal. You can roll that on. No need to pour/ mess with the slope.

Do not use cheap/mid priced stuff that is labeled "Concrete paint", it won't hold up.

The real question is, is it worth it?

You're looking at days of work and no guarantee that it won't crack again some place. I consider the damage shown to be that substantial that it probably makes sense to demolish the old patio and pour a new slab. Because there's always the chance that when it was first poured, mistakes were made - that you won't overcome with spot repair and a new to layer. And I guess you'd hate it do do all that work, only to have it crack again sometime in future.

If you have not worked with concrete and the materials needed before, I suggest you get a professional to look at this first.

Kind regards,
Oliver

 

[diogofcr]

Hi!

Honestly, where to start?

That is quite substantial damage. This is not something that is fixed with filling some of the holes/ spot repair.

First you need to further asses the actual damage. I can see cracks that seem to run below the top surface. All of these cracks need to be found and opened. All loose material removed, thoroughly.

The pictures tell only one side of the story, the real question is if that concrete was mixed and poured correctly.

If done professionally, you'd use a "hole saw"/core drill and analyze the concrete. Then a specialist would set out an exact procedure on how to fix this and what material is to be used for that.

Let's say you removed all the loose stuff and all cracks lie open.

You'd start with a primer, not just any primer but a bonding agent/coupling agent/adhesive-promoting agent especially for concrete.

Once that has dried, you can fill the cracks and holes.

Whatever you use to fill the cracks and holes has to be suitable for the depth of the cracks/holes and corresponding needed layers of material. I don't know the products you have linked, but the "structural" part in the Name of that Axton product, makes me think you are on the right track. You definitely need a product that is suitable for structural concrete repairs.

There are also epoxy (resin + curing agent) products available to repair the cracks, not so much for the holes.

Then I'd suggest using a mesh material that you place all over the (now closed) cracks, you use the primer to get it to stick. It's a good idea to use primer on the whole surface now.

Then you can make a new top surface/layer. For keeping the slope you need a material that won't run like water. So yeah, the self-leveling stuff, I won't recommend it. You need something with thicker consistency.

Finally, I'd suggest using epoxy flooring to get a robust, water tight seal. You can roll that on. No need to pour/ mess with the slope.

Do not use cheap/mid priced stuff that is labeled "Concrete paint", it won't hold up.

The real question is, is it worth it?

You're looking at days of work and no guarantee that it won't crack again some place. I consider the damage shown to be that substantial that it probably makes sense to demolish the old patio and pour a new slab. Because there's always the chance that when it was first poured, mistakes were made - that you won't overcome with spot repair and a new to layer. And I guess you'd hate it do do all that work, only to have it crack again sometime in future.

If you have not worked with concrete and the materials needed before, I suggest you get a professional to look at this first.

Kind regards,
Oliver

Hi Oliver,
First of all thank you so much for your help!
Sadly redoing all the slab is not really an option. I know it would be the best choice. My parents are the owners of the house and say it would be too expensive.

About assessing the damage. Could I use an angle grinder with a diamond blade and cut around the cracks so as to open them and see until where the damage goes?

Before filling the cracks and holes should I reapply a second layer of primer and this time not let it dry before pouring the "Axton product"? So it acts like glue to the new filler?

I didn't quite understand the part about the mesh material. Are you talking about rebar? You said "using a mesh material that you place all over the (now closed) cracks". Place over the closed cracks? Am I not supposed to put the rebar inside the holes instead?

About the epoxy flooring would I be able to apply tile over it? I think my family wants to make some kind of diy tile Mosaic in one section of the slab.

Thank you once again!
Best regards,
Diogo Raposo

 

[six-point socket II]

Hi Diogo,

Yes, you can use an angle grinder with diamond blade, but also keep a hammer & chisel/ demolition hammer close by.

No need to apply a second "wet" layer of primer prior to filling.

No rebar. It's comparable to jointing tape, but a mesh material and for concrete. This is also available as a fibre glass mat, for use with the epoxy filler. (If you prefer that.)

I thought you wanted to paint the top layer, that's why I recommended the epoxy flooring. If you want to tile it, no need for the epoxy flooring.

Kind regards,
Oliver

 

[Jiggy Joiner]

I’m with Oliver, it looks like it’s had it’s day to me. It looks more like a sharp sand and cement screed from the photos, as opposed to concrete. The layer is also too thin.

Not sure if you get much frost there but, it does look like frost damage.
Breaking out the top layer, and slabbing it would be another option that wouldn’t brake the bank.

 

[six-point socket II]

I agree, Jiggy! At least it's damage from water ingress over this long time, but quite possible also frost has played its roll in it.

It could also be, what we call "Betonfrass" or "Betonkrebs" in German language. It roughly translates to "concrete grub" or "concrete cancer". It's a chemical reaction. It happens when the concrete was made from pebble with too much soluble silicic acid left in it. Add water/ have water ingress over a prolonged time and you get the reaction.

Real problem: https://en.wikipedia.org/wiki/Alkali–silica_reaction

But then again, if you don't mind the work and want to take the risk of probable failure - you can try to fix this in a DIY approach with readily available materials.

But I can't give any product recommendations, as I have no idea what you can buy locally.

Kind regards,
Oliver

 

[Cheese]

A rather interesting problem. Basically it was the drain paths that deteriorated/spalled. The larger cracks below the surface worry me as they aren't just small cracks.

The rule of thumb is a spalled surface can be corrected if it is 1/3 or less the total thickness of the slab. Those large cracks are worrisome. 

I also wonder what those white brick-like things are below the surface?

 

[Oldwood]

If possible you might consider pouring a new slab over the old one. This is what I ended up doing when I had a similar problem. All the patch solutions I looked at had no guarantee of longevity.

The one caveat is to use a bond breaker between the old and new slabs.

This of course would only be an option if the extra height can be accommodated. 

 

[Holzhacker]

Look at www.abatron.com products.
Good reliable stuff, better than the box box crap.

 

[Nailed IT]

I would remove it and replace it.  Check the base material.  Make sure it is well drained and compacted.  Include a section of wire reinforcement for good measure.

 

[AlexThePalex]

If this concrete is only 10 years old it was bad from the start, like the mixture had too little water in it. The amount of damage here is huge and should simply not happen to properly poured concrete.

Concrete needs water in its reaction to cure properly, if there's too little water, the particles don't bind and you get this result. The parts that get to endure the most stress go first, but there's a good chance the entire slab is like this.

 

[diogofcr]

Everyone thank you for the help and suggestions!

I’m with Oliver, it looks like it’s had it’s day to me. It looks more like a sharp sand and cement screed from the photos, as opposed to concrete. The layer is also too thin.

Not sure if you get much frost there but, it does look like frost damage.
Breaking out the top layer, and slabbing it would be another option that wouldn’t brake the bank.

Yeah it is way too thin in my opinion. we can almost remove it all by hand.

Ahah here there is no frost.
I know that is the best option but the parents don't want that..... I know that this repair will probably fail again but oh well this is the only option
Thank you!

A rather interesting problem. Basically it was the drain paths that deteriorated/spalled. The larger cracks below the surface worry me as they aren't just small cracks.

The rule of thumb is a spalled surface can be corrected if it is 1/3 or less the total thickness of the slab. Those large cracks are worrisome. 

I also wonder what those white brick-like things are below the surface?

Yes the worst areas are where the water sat near the drain hole. Some cracks are huge.
You mean a combination of white "bricks" spaced around the patio? I also don't know. My guess is they used them to divide it by sections to make the slope to drain the water to the middle??

If possible you might consider pouring a new slab over the old one. This is what I ended up doing when I had a similar problem. All the patch solutions I looked at had no guarantee of longevity.

The one caveat is to use a bond breaker between the old and new slabs.

This of course would only be an option if the extra height can be accommodated. 

I will do some research about this but I don't think it is an option... Sadly my parents don't wanna do that even though it is the wise solution... Thank you!

I would remove it and replace it.  Check the base material.  Make sure it is well drained and compacted.  Include a section of wire reinforcement for good measure.

Thank you! I wanted to do this but sadly it is not an option.

If this concrete is only 10 years old it was bad from the start, like the mixture had too little water in it. The amount of damage here is huge and should simply not happen to properly poured concrete.

Concrete needs water in its reaction to cure properly, if there's too little water, the particles don't bind and you get this result. The parts that get to endure the most stress go first, but there's a good chance the entire slab is like this.

Yeah the guys who did this did a terrible job...