My brother will be helping his buddy level out of some his basement slab that apparently settled. He said from description its like a 8x10 portion that apparently sunk/settled near 1.5+ inches on one end from the start. He would rather not use SLC since its SO expensive and he would need so much so I thought concrete (sakrete 5000) thinned out with straight portland might do the job as well if he uses some prepping/bonding agent and cleans it REALLY well. I know the agg would be a pain in the shallow areas but might work better in the deep areas. I used a similar mix for my concrete counter (I KNOW not the same) and it is super strong.

What do you guys think? Dumb idea, or feasable?
Any other tips?

I should add they are carpeting over it when its done

 

Did the settlement affect the walls, or is there a gap of air between the wall and slab? It may be extreme, but concrete pumpers can level out slabs depending on where it is located. They could pump directly under the fallen slab portion and bring it back up to level. Check it out before trying to pour over an already problematic slab.

 

I'm confused that you're willing to thoroughly prep the area and use bonding agents but then the cost of self leveling is too much? If you're trying to do a proper job I don't know why you'd only go 80% of the way there.

But first I would determine why the slab has sunk. Is it still moving. You can tap on the floor with a heavy piece of wood and listen for a hollow sound that could indicate that something else is going on below the slab. If there is a void it's likely the floor will coninue to sink even after applying the leveling compound. Mud jacking companies, like Chandler mentioned, can inject grout under pressure under the slab. That would fill the voids and even return the floor to it's original level.

 

Ill forward that info. He can buy prepping agents in the big box for pennies compared to bags of SLC for 36$ a pop that will fill roughly 1/8"x3'CF lol.

Its really up to my brothers friend the route theyre willing to take, not mine. Im not honestly sure of the kids financial situation but I know he got the place for like 60K and its trashed.
My brothers is just staying there so he is helping him fix it up for now.
Ive personally never even seen it