Mechanical rebar splicing from existing-square to new-round 1

I've never used these unfortunately.

But since responses are lacking I'll throw something else out there: have you considered taking a coupon and seeing if a welding procedure could be fashioned? In splicing existing bar, even of structures around that age, it is not so infrequent to use bridging angles that come pre-welded to the splice bar. That way we only have to weld 1-half in the field.

Though you did mention space constraints so even if metallurgically possible it might not be feasible.

I think these assemblies are tested per some ASTM test, and only with standard deformed bar. Likely no one will sign off on you using them with twisted square bar. Could you cast some new concrete below, roughen the surface and dowel the two masses together, and keep your new bar close enough to be a non contact lap splice?

Thanks Enable and canwesteng:

We have welding as an option but it is in a crawl-space with very limited access and our least-preferred splicing option. But it is an option.

The square-section rebar is NOT twisted, it is square section with deformations, but that probably does not make is any easier for an 'approved assembly test'. I may well purchase some samples of grout-filled and shear-screw splices, take 2 sets x 3 rebar samples from the project and using some hydraulic rams I have build up a test frame and break them to failure to see that I get fracture in the old square rebar before other modes.

The application is NOT 'structure critical' type locations so an in-house test should be satisfactory.

BarSplice's ZAP SCREWLOK TRANSIITONS looks promising.

They state they are for "different sizes, or for connecting different configurations or shape".

Those might be really handy in my line of work. If you go that route / find something else that fits the bill would you mind reporting back here with how it worked / approx cost?

I shall indeed.

==> EDIT: I called BarSplice and spoke to engineering/technical and they have used ZAP SCREWLOK with old square rebar to new round, you just have to up the size of square by 1 size, so if #4-square to #4-round you would use #5/#4 transition ZAP SCREWLOK. However, no testing/approval/ESR for such use with square section.