[paul0317]

I am pouring a new slab for my RV. It will be outside in a covered shed. The slab is 40' X 50' 6" deep. My queston is can I put the Dowels in place before I pour and not have to drill them. I have 6 areas to pour and breaking it up into 2 pours 3 sections each day.

[parttime]

Hi paul and welcome to AMHD, when you say "dowels" if you mean rebar to tie the sections together? Then yes you can install it first. Good luck

[hkstroud]

Are you talking about installing anchor bolts or straps for the wall plates?

[paul0317]

Thanks for the response. I am new to this and learning. The concrete slabs are separate and I was going to tie them together and allow for expansion with out cracks. I found that you could drill one side and put rebar and then pour other slab. I think that allows the slab to contract with out moving. I was wondering if I could put the dowels in before I poured.
I am not even sure this is needed. Is just using the rebar for expansion joint sufficient for decreasing cracks. I am probably over thinking this.

[smearcase]

These smooth dowel types of joints have been used in highway concrete paving at contraction joints (every approx. 40 feet measured in the direction the vehicle travels) for a long time and were referred to as load transfer devices. They were normally placed at mid-point of the depth and supported on chairs (metal supports holding them in correct position-the chairs being embedded with the pour. Usually, both sides of the joint were placed in the same operation (continuous) and a joint sawed within about 12 hours max.
If you are just pouring one side of the joint per pour, you could probably build a wooden support sitting on the grade of the second pour, then remove for 2nd pour. The smooth dowels are usually greased to increase movement.

[Dr1757]

Paul over time all concrete is going to crack no matter what precautions or methods you use. Anytime I have added a concrete slab next to an existing slab I always drill 3/4 holes with a hammer drill and drove in pieces of rebar a foot long (6 inches into the old slab). This will tie the sections together and keep them level, and prevent separation.

If I were in your place I would pour it all at once and have expansion joints cut across it every 20 feet.

Hope this helps

[paul0317]

Yes I am pouring smaller section to be able to handle it with two people. I am adding a board to separate the pours for expansion. I was just reading and found out about the dowels. Never could find them at the Box stores so thinking I might make my own using pipe and rebar with grease in between. I am more concerned with moving up and down then side to side. The dowels sound like they would help with both.
Any comments on my home make dowel working or being a waste of time.
Need to change my name to the “weekend carpenter”.

[Dr1757]

The last slab I poured was 20' wide by 28' long using the 3/4 inch rebar at two foot intervals to tie it to the adjoining slab. I dug 24" deep footers and one 24" deep beam which ran length wise. This was 4 years ago and this addition has not moved. There have been some surface cracking which is normal but nothing serious. I don't think your going to accomplish much by using pipe and rebar to make a sliding connection. I would not use wood between your sections, it will rot away then you'll have fill the gap with some sort of filler. If you've never poured concrete before I would highly recommend having some experienced help, or spend the money and hire someone to do it for you.

[paul0317]

I should have been more clear with the use of board. I am using fiber board, I think it's called, to separate. Thanks for the help all. Not done building so might ask more.