Adding Portland cement powder to fibreglass resin

amandstu

Anyone tried this?

I have just done it and have got something like chemical metal or plastic padding.

I think it works out cheaper than buying those 250ml tins that are barely half full when you open them.

I cannot see how this can possibly work out well. Portland cement only achieves any structural integrity if it reacts with water chemically - a reverse of the chemical burning process. There is no water in Resin and so all you are doing is bulking the resin with inert filler.

amandstu

https://www.boards.ie/discussion/comment/118715531#Comment_118715531

That is the idea.To simply bulk up the resin and make it thicker.

I have used it to fill in holes in a rusty old water tank.

It seems to have hardened and stuck to the surface well enough

Because it is much more economical,I can use it more freely

I also had the idea to chop up fibre matting and mix it in but it was a bit clumpy and unworkable.

Deregos.

https://www.boards.ie/discussion/2058235368/adding-portland-cement-powder-to-fibreglass-resin

That's interesting, what fibreglass resin did you use?

amandstu

https://www.boards.ie/discussion/comment/118717467#Comment_118717467

The container reads"contains polyester resin in styrene"

The brand is Tricel and it needs a hardener that comes in liquid form in a small bottle

amandstu

Just want to point out that the pieces of this mixture that fell into water before I could apply it normally did not harden (normal fibreglass resin will harden under water) so I have to work out why that happened and also if the mixture that did harden will soften if under continuous water.

Lumen

Normal resin fillers are cheap and chemically inert so whilst this is interesting, it seems a bit risky for the sake a saving a few cents.

e.g. https://www.easycomposites.eu/filler-powders-and-additives

Lumen

So I think the problem is that your mixture is binder-binder, not binder-filler.

The cement and resin are doing the same job, except the cement can't do its job (at least immediately) as it's fixed in resin.

What happens over time, chemically? Don't know, but I imagine nothing good.

Better to use any inert filler, even sand.

There exist poly mortars, grouts and concrete mixes but in all cases cement is either absent or mixed in a way that it cures properly.

CJhaughey

Why not buy a larger quantity of polyester resin and do the job properly instead of trying freebaking with chemicals.

Either the job is worth doing correctly or its not.

amandstu

https://www.boards.ie/discussion/comment/118723905#Comment_118723905

I had been scratching my head for ages as to what inert filler I could use and yes sand came to mind ,as well as peat dust .

If I could buy clay in powdered form that might work as the finer the better would give a nice smooth ,workable material

When I thought of cement I thought that it would be pretty fine as well and that it chemical properties might well be "sealed" in by the fibreglass.

But I am uncertain as to how long that would last if the area was continuously wet (would have no problem otherwise ,I think)

I am only using this on an old water tank that I use for the garden and so I can correct any missteps along the way.

It is a very large object and irreplaceable on the market(you couldn't buy it easily in Ireland ,I think and it would cost a fortune if you could)

Silver sand is very fine and would be a better candidate than cement.

What I see happening with cement is micropores in the resin allowing water to get to the particles of cement at the surface - these would expand and fry off the surface allowing progressively more cement to be exposed in a catastrophic cascade. Might take months or years but just like rust once it started it would be totally unstoppable.

amandstu

https://www.boards.ie/discussion/comment/118739548#Comment_118739548

Yes ,I see that.I will probably coat the area I have done with pure fibreglass resin ,especially areas that will be underwater

If that doesn't work well I could try the silversand or some equivalent (can you buy powdered clay,I wonder)as necessary down the line.

Lumen

If you're buying filler then just buy the correct product for the job. It's not expensive.

There are plenty of online guides for resin filler selection.