Webber coarse quick 5-100 to blue concrete?

[Noas]

Hello!

From what I understand, you can use Webber coarse quick 5-100 on lightweight concrete to fill holes and similar tasks? I have plastered walls from 1953 that are probably lime plaster but have now recessed the electrical wiring into the walls, and thus need something to fill the grooves, which are about 5cm deep. I was planning to plaster 1cm at a time and water it endlessly... but then I found http://www.weber.se/betong-cement-vagglagning/produkter-och-system/vagglagningspackling/weber-vagglagning-snabb-grov-5-100.html which should work well for this purpose?

Has anyone tried this or can tell if there's a risk of Ettringite formation?

There's also a primer for absorbent materials like blåbetong.

Thanks!