dividing mono pour into 2 pours?

[tccracer]

I have a contractor who wants to do my garage footings and slab as 2 pours by dividing the space in half. He then says he will put some rebar through the 2x4 that will divide the pour. He says it will just act like a expansion joint.
Do I need to be concerned about this plan?.
Concerened about how much bar he uses?.
Any other issues doing it this way?.

Thanks in advance for any help!!



Robin

 

[HiHoSilver]

should be no problem for the slab, I am assuming he will remove the 2x4 for the second pour, He does however need to place exspantion joint material between the two pours, he should place the material about 1/4" below the top surface to create a pocket to seal the seam with EJ3 or other flexable sealer. (use a good commercial brand)


I also recomend spacing the rebar every 6" and place in each pour 24" deep.

I am not sure about the footings....I personally would not want to a 2 piece footer. but our soil and weather conditions here in WV are much different the Fl.

This might seem over kill, but is good insurnace that you will not have problem in the future.



I not a civil engineer, but work with them during projects for the company I work for.... also I stayed in a Holiday In last night....

 

[tccracer]

Thanks for the info.

I will talk with him about the footings. I am doing this up in Western NC. If I were home I would invite you over to see my vetts!

Robin

 

[HiHoSilver]

Thanks for the info.

I will talk with him about the footings. I am doing this up in Western NC. If I were home I would invite you over to see my vetts!

Robin

Good luck with the build, keep up posted!!

thanks for the invite, I need to figure out how to work form home so that I can live in Florida during the winters, cold/snow bites..
If you get time, post pics, I would like to see them.

The silver one as my avatar is a 2007 coupe, I also have a 1973 Convt, currently restoring (rolling chasis w/motor is complete). Progress has slowed since buying the 07....

 

[dxdexter]

I have a contractor who wants to do my garage footings and slab as 2 pours by dividing the space in half. He then says he will put some rebar through the 2x4 that will divide the pour. He says it will just act like a expansion joint.
Do I need to be concerned about this plan?.
Concerened about how much bar he uses?.
Any other issues doing it this way?.

Thanks in advance for any help!!



Robin

Separation between slab-on-grade placements is generally performed by placing smooth dowels as opposed to deformed reinforcing bar between each placement. The smooth bars will allow the slabs to move independently horizontally of each other, to allow for shrinkage, while giving vertical load carrying capacity between the control joint. Isolation material should not be necessary.

If you place smooth bars, then you should apply a bond breaker, such as grease, to one end to allow it to slide within the adjacent concrete. The bars should also be level and parallel to each other or you will lock the control joint.

 

[tccracer]

Dex,
What would you suggest for spacing of the bars? The slab is 30 feet wide where the 2 will join. Should I have the footings done first,then 1/2 the slab,smooth bars and then the other 1/2? If he wants to only do 1/2 the footings and slab with the bars is that ok?



Thanks for the advise. The total slab is about 3000 ft and no one here wants to do it as a mono.

 

[dxdexter]

Dex,
What would you suggest for spacing of the bars? The slab is 30 feet wide where the 2 will join. Should I have the footings done first,then 1/2 the slab,smooth bars and then the other 1/2? If he wants to only do 1/2 the footings and slab with the bars is that ok?



Thanks for the advise. The total slab is about 3000 ft and no one here wants to do it as a mono.

Only use the smooth bars for the slab, not in the walls or footings. In the walls and footings you just run the rebar into the next placement from the previous. When footings are placed in multiple placements then the contractor will generally end the concrete roughly 30 degree angle, so that the next placement will resume on top of the previous one thus creating a stronger joint. Relate it to a lap joint in woodworking. The walls will be a simple but joint, but it is prefered to have a keyway cast into the end.

With regard to slabs: On most commercial work we specify a 12" spacing between bars. Note that these are heavily traveled warehouse or retail settings and not your average residential construction. Most doweling is now held in place by pre-fabricated dowel baskets which are more or less a wire frame work to keep alignment of the bars or in some cases specially shaped shaped flat bars. It will be easy to align the dowels if the contractor uses a drill press to make the holes for the bars in the 2x bulkhead. This will produce a hole perpendicular with the form and as long as the forms are square the bars will be perpendicular and parallel.

The drawing below are the type generally used in concrete pavements, but they are scaled down for slabs-on-grade. The second picture will give you an idea of what I am speaking of with regard to de-bonding the bar. disregard the dimensions as they are not pertinent to this discussion.

 

[tccracer]

I think its starting to sink in.

I am using a 3 bar chair in a 16x16 footing. Should I add a couple more bars higher in the footing where the 2 pours meet?. I will do the one foot spacing in the slab for sure.

Again, THKS

Robin