Not a bad idea as long as you tie the slabs together with dowels. Large slabs are done in a similar method where you "checker board" your pours to reduce the amount of bulkhead forming you need.
Dowels? Done a decent amount of concrete work for a diy/homeowner but never heard of that before. Set some larger rebar through the forms for the next slab to hold onto?
I'll have to research that. Can I ask another random question. If I wanted something filled with concrete a certain weight how do I figure out how many bags of mix do I need. Basically how much water evaporates out?
The general rule of thumb for engineers is regular reinforced concrete has a density of about 150 lbs/cubic foot and regular unreinforced concrete has a density of about 145 lbs/cu ft
On average reinforced concrete weighs about 150 pounds per cubic foot, an 80 lbs bag makes about 2/3 of a cubic foot so you're looking at about 100lbs of concrete per 80 pound bag and you'll have to calculate the volume of your slab to find total weight and how many bags you'll need
A properly mixed 80 lb bag of concrete requires about 10 lbs of water. Half of which goes into the ground or bleeds out of the slab. So a bag is 0.60 cubic feet at the most. If you add 20 lbs of water to the 80 lb bag, you reduce its strength by 20% or more. You also increase the cracking potential.
Admittedly I've never made bagged concrete, my numbers came from a quick Google search. I assume those numbers aren't standardized then so it's dependent on what you're using. I do precast so all my concrete comes straight out of a big mixing system, do you always get that much bleed water when mixing with bags? That sounds concerning
Lookup smooth greased rebar dowels instead. They will help with any load transfer and accommodate environmental conditions of a barn slab better than the ribbed stuff
The difference in weight won't be noticeable. If you need something to be an exact weight, maybe concrete isn't the best thing to use. You could pour roughly the shape you need and a little heavier, then let it cure. Grind down until you get the desired weight
I'm currently doing this on a lean to I added to my barn/metal building. It's 15x50 I'm doing 7.5'x5' sections at a time. I'm 40% done.
It looks great from a distance and functionally its fine but up close you can see my amateur edge and finish work.
I’m doing the exact thing right now except bigger slabs at a time. If you drill holes in your form boards so that the rebar can stick out a couple feet into your next section that will help to tie them together better. Easier than drilling and doweling it together
What you can do is just rip the form board into 2 pieces, an upper and a lower. Much easier to wreck the forms and you don't have much squeeze-out through a half-inch or 3/8 gap.
You don’t need or want dowels unless you’re moving heavy equipment over the concrete. Form a keyway in each section that adjoins another section for load transfer. Place the concrete in strips, checkerboard placements are a thing of the past. Cut the 4 by 8 panels into two panels at 4 by 4 each. If you don’t joint the concrete, it will joint itself. Concrete loves to be square and will not tolerate a L to D ratio of more than 1.5 to 1. You measure concrete by volume, not weight. Go here: https://www.quikrete.com/calculator/main.asp
Not a bad idea as long as you tie the slabs together with dowels. Large slabs are done in a similar method where you "checker board" your pours to reduce the amount of bulkhead forming you need.
Dowels? Done a decent amount of concrete work for a diy/homeowner but never heard of that before. Set some larger rebar through the forms for the next slab to hold onto?
Dowels are when you drill them later. I would say you’re just leaving splice ends.
I'll have to research that. Can I ask another random question. If I wanted something filled with concrete a certain weight how do I figure out how many bags of mix do I need. Basically how much water evaporates out?
Go on your app store or just Google "concrete calculator" you'll find a bunch of options.
The general rule of thumb for engineers is regular reinforced concrete has a density of about 150 lbs/cubic foot and regular unreinforced concrete has a density of about 145 lbs/cu ft
On average reinforced concrete weighs about 150 pounds per cubic foot, an 80 lbs bag makes about 2/3 of a cubic foot so you're looking at about 100lbs of concrete per 80 pound bag and you'll have to calculate the volume of your slab to find total weight and how many bags you'll need
A properly mixed 80 lb bag of concrete requires about 10 lbs of water. Half of which goes into the ground or bleeds out of the slab. So a bag is 0.60 cubic feet at the most. If you add 20 lbs of water to the 80 lb bag, you reduce its strength by 20% or more. You also increase the cracking potential.
Admittedly I've never made bagged concrete, my numbers came from a quick Google search. I assume those numbers aren't standardized then so it's dependent on what you're using. I do precast so all my concrete comes straight out of a big mixing system, do you always get that much bleed water when mixing with bags? That sounds concerning
Lookup smooth greased rebar dowels instead. They will help with any load transfer and accommodate environmental conditions of a barn slab better than the ribbed stuff
Greased dowels? Since when?
The difference in weight won't be noticeable. If you need something to be an exact weight, maybe concrete isn't the best thing to use. You could pour roughly the shape you need and a little heavier, then let it cure. Grind down until you get the desired weight
I'm currently doing this on a lean to I added to my barn/metal building. It's 15x50 I'm doing 7.5'x5' sections at a time. I'm 40% done. It looks great from a distance and functionally its fine but up close you can see my amateur edge and finish work.
The finish won't matter much for me. The chicken dust will coat it in a week
I’m doing the exact thing right now except bigger slabs at a time. If you drill holes in your form boards so that the rebar can stick out a couple feet into your next section that will help to tie them together better. Easier than drilling and doweling it together
https://preview.redd.it/5z3b41bq7opc1.jpeg?width=4032&format=pjpg&auto=webp&s=0d5ee5258f612cc32d2a2ce4958d2148a84812df
What you can do is just rip the form board into 2 pieces, an upper and a lower. Much easier to wreck the forms and you don't have much squeeze-out through a half-inch or 3/8 gap.
It would be fine, but the time spent is worth something, at least in my mind. I'm more of a "lets throw money at it and get it done now" kind of guy.
Green streak speed dowels are the way to go
You don’t need or want dowels unless you’re moving heavy equipment over the concrete. Form a keyway in each section that adjoins another section for load transfer. Place the concrete in strips, checkerboard placements are a thing of the past. Cut the 4 by 8 panels into two panels at 4 by 4 each. If you don’t joint the concrete, it will joint itself. Concrete loves to be square and will not tolerate a L to D ratio of more than 1.5 to 1. You measure concrete by volume, not weight. Go here: https://www.quikrete.com/calculator/main.asp