If you just laid the slabs, then you probably don’t have to do this. Just make sure there’s no dirt in the gaps.
The mixture might be different depending on the product you’re using. Always read and follow the instructions provided. The amount of mortar you make depends on how many gaps you’re filling. If you need more, you can always mix it quickly.
If you’re mixing a lot of mortar for a large area, then an automatic cement mixer will make the job a lot faster. For normal patchwork, mixing by hand with a trowel should work fine.
Don’t use a hose or dump the water in with a bucket. It’s easy to accidentally waterlog the mortar this way. If the mixture is too wet, add more cement and sand at a 1:4 ratio to thicken it up. Make sure you’ve mixed the sand and cement together before adding water. Otherwise, the mixture will be uneven.
For a quick test, pick up a bit of mortar and squeeze it in your hand. It should hold its shape when you open your hand.
Don’t worry if you scooped out too much. You can always use any excess mortar for the rest of the gaps.
If the mortar overflows, just scrape it forward to fill more of the gap. Tap the trowel on the slab if some of the mortar is stuck to it.
Don’t apply too much pressure. The point is to just flatten the top of the mortar, not pack it in tightly. If the slabs aren’t even, then pack the mortar so it’s even with the lower slab. Don’t worry if there’s some excess mortar left on the side of the slabs. You can clean that up later.
Some masons like to use improvised jointing tools, like a piece of pipe that fits the gap. You could use something like this if you don’t have a jointing tool.
Don’t worry about the mortar staining or sticking to the slabs. As long as it wasn’t too wet, this won’t be a problem. If the mortar is watery, scrub it off with a damp sponge.
The curing time might vary depending on the product you use. Always read and follow the instructions that come with the cement.
