Mortar mix for internal blockwork 7:1

[stuart45]

I think it is a matter of incompetency. They assume a bag of cement is 5 shovels, so they cut a bag in half (2.5 shovels), and then add 10 shovels of sand ( 4 * 2.5 = 10 ).

Instead of cutting the cement bag in half, they should empty in on the ground and shovel the necessary quantity in, with the same shovel as the one used for the sand.

That's not the way to do it. On a windy day you will lose a lot of cement, plus what goes into the ground. For more accurate gauges as with repointing bucket gauging is the best method for colour consistency. Using a shovel can vary the gauge if you look at what is there with wet sand compared to a shovel of dry OPC powder.
With blockwork that is going to be rendered or plastered it's not so important.
You can usually tell by the colour if it's too weak, but remember that OPC mortar is tested at 28 days, so in the first week it won't have reached it's max strength. It will also cure slower if the blocks are damp and the weather is cool, which is quite a good thing. Also if the joints are not tooled up which compresses the joints they will probably feel a bit weaker to start with. The compressive strength of even a weak mortar is usually enough for most loads in domestic work. Weak mortars only really suffer when the joints are exposed to the weather as in face work.
BTW I wouldn't test the work by pushing the walls. Masonry, especially 4 inch blockwork isn't renowned for it's lateral strength.

 

[A Trowel]

Isn’t it called a half bag mixer for reason ?

 

[jeds]

Half a bag per mix is pretty universal. You just need to get the sand right.

 

[akist]

I found out that a bag of cement is 4 shovels, maybe less, and not 5 shovels as the labourer had thought. His boss has now asked him to shovel the cement in and it is quite different now.