As best practice we would not suggest using Postcrete for a child’s climbing frame as there is no guaranteed compressive strength – it is ideal for supporting fence posts and smaller gateposts.

We would suggest using your High Strength Concrete instead which is guaranteed 40N, again ready to use just add water but is not fast setting and normally takes 2-3 hours to set. Based on measurements given you would need just over 11 bags per hole.

Kind regards