Concrete filler/repair mortar/patching mortar for kitchen countertop

[ensamresande]

I'm posting the thread in this forum as it has more to do with building materials than kitchens.

Anyway, I'm planning for an upcoming kitchen renovation and have now come to the countertop. I want to have some form of stone or composite material, but due to a "challenging" layout in the kitchen with several angles and 45-degree corner cabinets, there will need to be a number of joints in the countertop if it's done traditionally.

Initially, I had the idea of casting the entire countertop in concrete on-site, but due to various reasons, I'm starting to have second thoughts.

Now I'm considering if it might be possible instead to lay some form of board (like particle board, form plywood, waterproof board, or non-cast concrete), and then layer everything with a few centimeters of concrete filler/repair mortar (followed by the same finishing as a pure concrete slab; likely hard wax oil).

The products I have found so far that may work are:

Ardex A 45
Ardex A 46
Combimix Concrete Filler
Weber Concrete Filler
Weber Rep 45 Repair Mortar
Weber Repair Mortar

All of these are listed as suitable for repairing stair noses and similar, which should be significantly more exposed than a kitchen countertop. Does anyone have experience with these products, how they differ, any similar projects, or any other input to offer?

 

[ensamresande]

Yesterday I talked with Brukspecialisten here in Gothenburg.

After some discussion, we concluded that I want a mortar with a grain size of <1 mm, which is dense and has high compressive strength, and if possible, is also thixotropic (to simplify the "plastering").

The mortar that fulfilled this best by far was Bemix 310 High Tech; which I subsequently bought 3 bags of.

I will return with an update in a few weeks when the project becomes relevant.

 

[yonna]

Interesting: I have a damage at the edge of the sink on my (homemade) concrete countertop that has an integrated sink and cooktop. The damage is extremely annoying (I cover it with a towel when I have guests ) but I haven't tried to solve the problem since the future plan is to replace the countertop with a new one from Landskrona Rostfria - when I can afford it. Your suggestion with Bemix 310 might be interesting. I need a maximum of 1/2 kilo ...

 

[ensamresande]

If you have an existing countertop in regular concrete, I don't think you need such a "high quality" mix (>70 MPa) like Bemix 310; the rest of the countertop is still "regular" concrete.

I would probably go with Combimix Betongspackel, which is sold in 10 kg bags at Bauhaus for about 200 kr; it's just cement and fine sand, so it will likely provide a very similar surface to the rest of the countertop.

 

[ptk]

How did it go @ensamresande?

 

[ensamresande]

How did it go @ensamresande?

It ended up with me making the countertop in 22 mm particle board and then cast it with Finja 540 Top White colored with black iron oxide to the right gray shade. Then sanded and treated with hard wax oil. A few years later, I'm still very pleased.

 

[ptk]

Aha so you skipped Bemix 310? Why is that?

 

[ensamresande]

Aha so you skipped Bemix 310? Why?

Floor leveling compound works better in such thin layers (about 20 mm) and is more flexible, reducing the risk of cracks.
Floor leveling compound on chipboard also felt most correct and least improvised, it's how you cast floors.

 

[ptk]

Floor leveling compound is runny. How did you cast the sides of the slab? And the underside?

 

[ensamresande]

Floor leveling compound is runny. How did you cast the sides of the board? And the underside?

I built a mold around it. The underside is not cast but is the particleboard.

 

[ptk]

Do you have to prime the particle board?

 

[ensamresande]

Do you have to prime the particleboard?

Of course. And reinforcement mesh. Do the same as for any floor.

 

[ptk]

Is reinforcement usually used for floor leveling compound? I didn't know that. But of course, it probably doesn't hurt anyway.