أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
Spacers should be made from the same grade of concrete, it should be cured by water for7 days at least before use them
Same or higher grade, if you have many grade of concrete for different structures/element.. Prefer to make spacer of highest grade to avoid any non conformance..