I am going to renovate the outdoor staircase a bit to later cover it with granite tiles. I need to cast between a landing and a wall that is under the landing. How do you do this? Once the form is in place, you can't reach in to pour the concrete, plus I want to get 100% fill.
Could you form and cast with regular concrete and leave a small gap at the top that you then form and fill with expanding concrete in some way? (If I understand how expanding concrete works, that is...). I might be able to cut into the concrete slab a little with the diamond cutter so you get a hole to fill.
You use expanding concrete to cast all the way since it fills out better than regular concrete. To be able to fill the mold, you make holes at the top with c/c 300mm spacing and attach a small trough that you pour the concrete into, which also ensures that the concrete stays at the right height until it has set. The wedge that forms in the concrete is cut away with a knife before it has fully cured. It is important to pour from one direction; otherwise, air pockets may form.
The holes are sufficient at 50x50mm. Feel free to make the funnels a bit higher than what you're casting because concrete can flow into the form if needed. I usually jukka a bit in the concrete with a reinforcing bar to make sure it has filled out properly.
