oceanobob
Senior Member
We epoxy installed the square dowels having the trick gizmo (from PNA) and the two rebar mats, the pic shows detailing at the (sawn) crack control joint to have the new concrete align the joints with the existing concrete.
These are #4s at 12"oc and we use the grade 40s cause the modulus of 40 and 60 are the same, and we dont expect the rebar to ever Yield. That big blob at the end would normally have to go since it locks the concrete but that happened to be in the end portion of the Work and that section had to be hard dowelled since it is close/adjacent to the metal building frame.....from this point (where the rebars dive) to the other end at 80 foot away is where we will be dealt the cards that address the shrinkage, ergo the dowels.
Faces of existing slab carefully ground to make sure no keys etc and being coated with some cure and seal as a bond breaker.
Foam (felt) would probably be better but it makes the finish fugly at the joint .... after the pour on wet saw day we run the saw down the joint where the new meets the old and then (later) fill all the saw joints w semi rigid. That black felt was once good but is now lame: it falls apart w/i one year and it is the epitome of less than desired appearance.
(Ronsii - when we removed the tape over the dowel holes we checked all the holes for any dust and there was none, clean as we left them LOL.....much nicer to drill when the excavation is empty than to wait until the end and fight the grade and the steel etc. My opinion.)
Chairs are called Standees and we made em on a bender but they can be bought from others, simply spread the legs to change the ht. Goal is the standee is over a dobie. Lotta heavies walking on the upper mat.
These are #4s at 12"oc and we use the grade 40s cause the modulus of 40 and 60 are the same, and we dont expect the rebar to ever Yield. That big blob at the end would normally have to go since it locks the concrete but that happened to be in the end portion of the Work and that section had to be hard dowelled since it is close/adjacent to the metal building frame.....from this point (where the rebars dive) to the other end at 80 foot away is where we will be dealt the cards that address the shrinkage, ergo the dowels.
Faces of existing slab carefully ground to make sure no keys etc and being coated with some cure and seal as a bond breaker.
Foam (felt) would probably be better but it makes the finish fugly at the joint .... after the pour on wet saw day we run the saw down the joint where the new meets the old and then (later) fill all the saw joints w semi rigid. That black felt was once good but is now lame: it falls apart w/i one year and it is the epitome of less than desired appearance.
(Ronsii - when we removed the tape over the dowel holes we checked all the holes for any dust and there was none, clean as we left them LOL.....much nicer to drill when the excavation is empty than to wait until the end and fight the grade and the steel etc. My opinion.)
Chairs are called Standees and we made em on a bender but they can be bought from others, simply spread the legs to change the ht. Goal is the standee is over a dobie. Lotta heavies walking on the upper mat.