Mike

I know that we are trying to get your products over here, and maybe one day we will have some success.  In the meantime, we have to make do with the local concrete repair mortars.  Most of these are polymer modified ... but still require curing if you read the manufacturers instructions (and even so called good tradesmen don't seem to be able to do that).

With regard to reinforcement, I guess I have a fundamental problem with patches being installed without reinforcement and dowels anywhere that the patches are unsupported or on the underside of projecting courses.  And unfortunately, that represents a lot of our patches.  Depth is usually in the region of 1-1.5"  (25-35mm) - if I have to go to 2-3" (50-75mm) then I will specify an indent because I don't want that sort of buildup in my patches.

Also, my dowels are typically only 3mm (1/8") and my reinforcement is usually 1.2mm diameter wire (1/20").  I know I don't get great cover, but my stainless is not going to corrode, and at that size, my differential thermal expansion is less of a problem.

I also limit the maximum size of my patches to about 400-500 mm (16-20") in dimension - I really don't like the idea of the differential thermal expansion between the patch and the stone for such large areas.

I know that theoretically these can be avoided ... but I can't get good repair mortars, let alone good tradesmen, and as for the fee to inspect on site ... forget it!  I'm lucky if I can get a fee to document the work properly sometimes!

Oh well, got that off my chest ... look forward to your comments.  And yes, I hope to try again to spec your repair mortar in the not too distant future.

Cheers

david

>>> "Michael P. Edison" <[log in to unmask]> 20/12/99 15:17:15 >>>
Message text written by david west on "BP - \"Is this the list with all the
ivy haters?\""
>  However, the stone indents are quicker - because I don't make them cure
the indents for several days - and this saves them money.  On one project,
the contractor voluntarily substituted stone indents for patches because it
saved him time!!!<

Now, David, if you had been using a latex-modified repair mortar you could
have eliminated most if not all of that wet curing!

>Note that when I spec patch repair, I require dressing back of the stone
to sound material, and use of stainless steel dowels and reinforcement in
the patch on all but the smallest of patches ... which makes it more
difficult for the patch repair man!<

Stainless steel dowels should only be used on patches more than about 2"
(50 cm?) in depth. That's because patches, like properly placed concrete
construction, should cover the end of the dowels with at least 1/2 to 3/4"
depth for latex-modified repair mortar, 1" for unmodified mortar. So unless
the repairs are pretty deep, dowels are unlikely to be properly covered and
as a result they may tend to induce cracking. As for reinforcement, I have
seen problems with maintaining proper cover there as well, particularly on
windy sites. Low shrinkage/low modulus repair mortars should be able to
endure without additional reinforcement, as long as the spacing between the
dowels is kept reasonably tight.

Mike E.