Patching A Concrete Fountain

[petec]

Well, I cracked it. It slipped out of my hands and hit the sidewalk. I would like to "paste" the three pieces back together. One problem is the mass of the thing. My weight lifter son says he is sure the largest piece weighs over 90 kg. The whole thing is less then 65 cm in diameter.
450880450879
My first thought was RTV it together but I am sure that when I put it back on the pedestal (which is less then 1/2 the diameter of the piece) the RTV won't have enough strength to hold it together.

I thought if I could get a 1 to 1.5 cm thick slab of aluminum, say 60x60 cm I could cut off corners and use it as a base. But the big box stores don't have anything near 1 to 1.5 cm thick.

I don't think exterior plywood would be strong enough and could stand up to the weather "forever".

Maybe an 45x45 cm ceramic tile floor piece?????

Any other advice?

What about an adhesive to use rather then RTV?

Note, I'm from the US and had to "think metric" to create this.
1000 pardons if I goofed.

Thanks


Pete

[Beardy]

Epoxy glue will hold it together just fine. I am not sure what brands you have available to you over there but companies like Epirez or Megapoxy would have something suitable but there would be many others available to choose from
Look up concrete patching/ repairs products and you will find something to do the job

[joe greiner]

What he said. Use a 30-minute epoxy to provide sufficient working time. "Clamp" with stout rubber bands made from bicycle inner tubes.

Cheers,
Joe

[petec]

I think I should have included a full image. I attached it now. I am concerned about the diameter of the pedestal verses the large bowel. And then the fact that the weight of the combined smaller bowel and imitation "pump handle" is all on one of the sections that broke off.


And, the surfaces that would have the epoxy are somewhat "crumbly". With all that weight the joint might separate just "behind" the epoxy.

Do you think that should be a concern?



450909

[petec]

What he said. Use a 30-minute epoxy to provide sufficient working time. "Clamp" with stout rubber bands made from bicycle inner tubes.

Cheers,
Joe

I was thinking I would use a ratchet tie down:
https://www.lowes.com/pd/SmartStraps-2-in-x-27-ft-Ratchet-Tie-Down/3740799

[Beardy]

All you can do is try it and see how it goes but the epoxy will be stronger than the concrete. The epoxies I was referring to before like epirez have a primer that will seal of the broken face of the bowl for better adhesion before bonding the faces together
You could also fibreglass the interior and underside for additional strength

[petec]

Well, I don't know. I was just out in the garage looking at the pieces and feeling the weight.
I am pretty convinced I need some support across the bottom.
An aluminum plate is many hundreds of $$$$
Maybe two side by side pieces of pressure treated 2x12. (In the states that is a pine board ~3.8x30 cm).
Epoxy the pieces together and RTV the whole thing to the boards.

Any ideas about what could go wrong with that?
I am still open to alternatives.

Pete

[pippin88]

You could remake it.

You could make a mold using the broken one.

Sent from my SM-G970F using Tapatalk

[dusteater]

Maybe you could make a base with high strength concrete well and truly reinforced.

[petec]

I'm liking the base idea.
Work with me a little.
I am thinking that I should epoxy the pieces together and strap them tight.
Then use it as a mold for a "plate" that would be the base under it.
That would make it maybe 8 to 10 cm smaller in diameter and there would be a cutout where the third piece fits but I don't think that will have much effect.
I would line the mold with plastic and pour in the mix.

Now for the mix, I ran into something they call UHPC (ultra high performance concrete) but I can't seem to find a place that sells a "bag". I did find a "formula"

https://www.hunker.com/12151327/how-to-make-ultra-high-performance-concrete

(https://www.hunker.com/12151327/how-to-make-ultra-high-performance-concrete)

But it looks like a lot of work.
The "regular high strength" stuff says "at least 2 inches (5 cm) " thick.
I think I can live with that thickness but not much more.
For reinforcing, rebar? screen?
I'm a little concerned that there will be some tension (vs compression...concrete is good at handling compression not tension) toward the edge that is away from the pedestal.
The pedestal is positioned more toward the back to offset the weight of the smaller bowl and "pump handle" thingy.

I could use some additional advice on this method.

[dusteater]

I might be talking through my proverbial , but most of the strength would be in the reinforcing , I don`t know if this is practical but a heavy duty steel plate with appropriate amount of holes to retain strength and allow full bonding of concrete or something similar.Just an idea.

[Beardy]

I don’t think your concrete idea is going to be of much use to you, it will need to be too thick before it achieves any structural integrity. Epoxies and polyester resins are at least twice as strong as concrete and does not require the thickness for strength

What they do to reinforce cracks with 20mm thick slabs of natural stone like granite, marble, limestone etc for kitchen bench tops etc is cut slots in the back of the sheet across the cracks and epoxy glue a thin reinforcement rod in the groove, they then Epoxy a sheet of fibreglass matting across the whole bottom of the slab.

[petec]

I don’t think your concrete idea is going to be of much use to you, it will need to be too thick before it achieves any structural integrity. Epoxies and polyester resins are at least twice as strong as concrete and does not require the thickness for strength

What they do to reinforce cracks with 20mm thick slabs of natural stone like granite, marble, limestone etc for kitchen bench tops etc is cut slots in the back of the sheet across the cracks and epoxy glue a thin reinforcement rod in the groove, they then Epoxy a sheet of fiberglass matting across the whole bottom of the slab.

That idea triggers two things.
(1) Are you saying I can use the existing bowl as a mold for an epoxy or polyester slab to be used under the bowl? What would the material be called?
(2) I actually have 2 slabs of granite counter top (about 3 cm thick) that the previous owner left behind. (It used to be one slab that cracked about in half.) Both are far too big. Should I think about getting one trimmed to fit under the bowl?

[Beardy]

You could trim the piece of granite you have to size and glue it ti the underside for support. Just buy a cheap diamond blade for your grinder and do it yourself

[petec]

You could trim the piece of granite you have to size and glue it ti the underside for support. Just buy a cheap diamond blade for your grinder and do it yourself

I have not used a diamond blade in my angle grinder. I estimate the total circumference might be 2m. The material is around 3cm thick. Would one blade last that long.
I suppose I could keep a water hose on it to cool it.

Do you really think that would work?

[Beardy]

Yes a blade should do it for you,it is a bit of an open question as blade qualities vary but you should be fine with that

[petec]

Well I thought I should report that I did something to solve this problem in case someone else has a similar problem.
Please forgive me for not using the metric system. All the material is sized in inches. I'll switch to metric at the end.

So, I was wandering through my local building supply store and spotted a sheet of pressure treated exterior plywood. It was 24" by 48" by 3/4" ("= inches) and cost $14 (less then a case of beer......Fosters???). The bowl I am repairing is about 26" in diameter and has a "bulge" out the back side.

I cut the plywood in half making two 24"x24" sheets and glued them together with construction adhesive. Then I cut the shape with a saber saw, including the bulge by placing it on the diagonal.
Then I glued the concrete pieces together and to the sheets using:
https://retail.usa.sika.com/en/produ...ction-adhesive (https://retail.usa.sika.com/en/products/adhesives/multi-purpose/sikabondr-construction-adhesive)
I considered epoxy but thought this would allow a little flex and it was about 1/3 the cost of epoxy.
I then bound the concrete parts together with:
https://www.lowes.com/pd/SmartStraps...e-Down/3740799 (https://www.lowes.com/pd/SmartStraps-2-in-x-27-ft-Ratchet-Tie-Down/3740799)
After a few days I considered it done and painted the edges with gray oil based paint and put it in place outside on the base.
Final size in "real dimensions", 61 cm diameter with 10 cm "bulge'. About 3.8 cm thick.

Things I could have done better.
The part I made is too large. I didn't consider that the edge of the bowl tapers toward the bottom so it is barely as large as the part. So it is very visible. i wanted it to be set back from the edge.
I wanted to sand the rim and round the edge under but I couldn't. The table I set it on to do the work started to give me concern that it would hold up. All the parts together must weigh 150 kg and I was afraid the side pressure of the sander might be the straw that breaks the camel's back.

So, it could have been better but now it is time to crack open that Foster's . ;-)

Thanks everyone for all the great ideas and guidance.