R & R warehouse floor

[CM1995]

Good job Bob. I've enjoyed reading the updates on this project.

Those orange plastic "dowels", tell us more about those. I have never seen them.

I have a one man line concrete pumping outfit we've used in the past. Like yours, he's not the cheapest but when you need a line pump he's the one I call. I prefer owner operators than using larger outfits.

 

[oceanobob]

When doing construction joints, the load transfer across the joint has been a topical evolution involving such things as smooth dowels, key forms, or rebar (&/or combinations). Sometimes the form is drilled for rebar but the form becomes quite obstinate to remove from the hardened concrete. One slab, being ahead by virtue of schedule, is also shrinking and moving accordingly so I elected to try the diamond dowel system made by pna. Another variant is to remove the form then drill and epoxy a smooth round dowel, or one could install a sleeve form for a round dowel is also available. In summary, there are a few options.
I figured the notable surface area of the plate would provide significant load capability and readily allow shrinkage in two directions in the given plane.
We painted the plate with SW's Macropoxy epoxy to provide corrosion protection.
The pics show skim cutting the cream (1/8" or less) from the form at the inside face plane (although many insist necessary to keep the form top perfectly clean), a grinder cut off wheel to remove the nails, and the dowels installed in the pocket form. The level is shown as a straight edge to show the care to keep the surface flat in the vicinity of the slab edge (ie no edger tool allowed).

 

[oceanobob]

And two more pics to follow the above...

 

[CM1995]

Thanks for taking the time to explain and take pics of the system Bob. How does it compare in cost to smooth dowels?

 

[oceanobob]

We got the diamonds (pocket and plate) for about $3.00 each and effectively almost $1 ea for the UPS across the state.

A twenty foot square dowel uncut of HR is delivered to our job at around $.50 per foot and the square dowel uncut of CR is $1.50 per foot; I would surmise this is a similar budget for a round bar.

Pls note, the performance of a plain dowel (drilled/glued/balance greased) isn't considered similar to the square or round dowel with a "sleeve contrivance" that allows for shrinkage movement in two directions within the slab but allows no vertical movement for load transfer criteria. A plain dowel requires form drilling or slab drilling then epoxy set. For me, there are plenty of times where a simple couple/few smooth dowels are fine and we drill & glue em, but in this case we had a slab to slab Construction Joint for a notable distance and we are hoping the additional feature of sideways slip for shrinkage may help reduce future cracking while allowing decent performance with the forklifts and their hard tires and loadings.

Sorry, I didn't get the price of the smooth round dowel with the feature involving the nail onto the form sleeves. And the square dowel with the sleeve doesn't come with a nail onto the form sleeve as it seems to be intended for drilling and epoxy setting.

Also for musing: The dowel bar setup that comes with a basket is not used at a Construction Joint and it 'functions / has involvement' with aggregate interlock .... just for commentary because while there is no drilling it isn't really for comparison due to it's different application. Add into the overall recipe that some regions have little shrinkage and/or they choose to not place reinforcing steel in the slab....then these baskets at the (sawn) crack control joints subject to the decision for aggregate interlock alone or a dowel basket in the event the joint opens wider than the aggregate interlock can affect.

 

[CM1995]

That's cheaper than I thought they would be Bob, I was thinking in the $6-8 each range. The ease of installation and less labor makes it a no brainer.

Your craftsmanship is spot on, I don't see that quality of concrete forming and finishing very often.

 

[oceanobob]

Center bay pour ready for tomorrow and almost closed back the dock wall where we had cut that access passageway.

Had to slightly skew the slab saw cut lines as the one row of columns didn't directly align to the other row of columns. The rebar is intentionally set to not "interfere" with the saw cut crack control joints, for example there are no rebar lap joints in any saw cut joints as that would effectively double the restraint in that location.

The CMU (speedblock type) wall curb base and block were completed in about 3 hrs using fast set concrete products also sold at HD and fyi these don't use portland cement but instead are made w calcium aluminate related cements. Block to be solid grouted w 3/8" concrete in the cells as soon as we complete concrete floor.

 

[movindirt]

Looks great! Did you break the block cores down to hold the rebar? What was the reasoning going with a CMU wall as opposed to a poured wall thats pinned to the sides?

 

[oceanobob]

These blocks are sold as one sees them; notice the no mortar on the vertical butts and the center is indeed low for the 'bond beam' horizontal rebar.
Since the (e) dock has a face with block existing, for a quasi "better match" we selected the CMU (concrete masonry unit) in lieu of CIP (cast in place). The horizontal rebars in the CMU are epoxy doweled into the existing block (pinned to the existing wall).

**

Some interesting concrete tools: besides the usual wood bull float, a resin float and a magnesium float at around 4', shown in a pic is a channel float and a pan; last pass being put on the slab. The channel float helps with bumps etc after floating and also after panning. 36" pan is the size and this is the bottom side, the other side has cleats which engage the power trowel blades.

The pan for the power trowel allows one to get on the slab earlier than std combination blades and helps fill holes etc and make the surface profile with improved flatness (in concrete worker lingo: reduces the mumps/lumps).

One more bay (and the dock) to go.

 

[oceanobob]

Last bay with rebar, dock block work completed, grouted all cells, backfilled and trimmed edges of dock flatwork to make neat lines. Mini hauled down off the dock.

Small curve ball: I had planned to fit the new C channel into the other segments and weld it up w some 7018....then I suddenly realized the segments' disrepair is signified by their movement under any reasonable typical load such as a semitrailer backing in or a forklift crossing and this regular movement will certainly create grief and early demise of the new channel's new concrete....thus I must isolate the new C Channel from these loose pieces and am thinking prolly won't ever weld it to the existing loose segments and will ultimately have to remove them and conduct a repair.

Close examination behind the channels (where we can see) shows necked down rebar welded to the channel which likely occurred as a rust rub wear rust rub wear cycle until they were so small they broke.

Seems welding the leg of the L gives decent fillet weld length but the radius of that L gives a chance for some flexing whereas I could switch the weld idea to a style similar to a stud weld where the rebar would be butted straight in and not bent .... and yes these are welding grade rebars, a whole $3 more than std grade 40.

 

[CM1995]

I would weld the bar straight into the C- channel like a standard imbed. Let the welded bars extended back into the slab pour several feet if not the distance of the new pour.

 

[Delmer]

I like the 1/4" by 4" strap repair. Why not do something just better enough the whole distance? 3/16 x 2' plate welded to the top of the C channel and bolted to the slab every foot along the edge. Only you'd need to keep the looseness from working the bolts loose, bolt the plate to C channel in a way that allows for that movement, or clean and grout behind that loose channel.

Thanks for the concrete education. Very informative.

 

[oceanobob]

As to the existing dock with the loose channel, we had to add that strap to keep operations going....for a repair, we will likely cut back the edge (say 2 or 3 feet) of the dock and replace the channel along with the concrete but not possible until this dock has concrete placed, cured and made ready for trucks. BTW those concrete screws don't really perform super good with this type of duty as they loosen in a week or so. So far, they do tighten back up and we hope that patch holds while we get this other dock ready.

Here are some pictures of the channel and end caps with eleven #4 *bars on the top row and these are about 3'6" long, and seven #4 *bars about 18" long on the lower row...the *bars at the ends of the channel are attached w/ a flare/j groove weld to the channel cap and the rest of the *bars butt and are fillet welded all the way around w 7018 with great care to create no undercut on the *bar.
*Welding grade rebar.

Yes, the channel bowed just badly enough (due to the rebar welding) although it was tacked to the other half of the channel as a strongback. To fix: note the rosebud and the water in the sprayer. Heated a few wedges, red hot not necessary nor required and then cooled via the use of the water [to preclude heat soaking]. The load binder with the push-stick cause a modicum of force, just barely enough to shift it into the restraint mode.

The formwork is beveled to make the chamfer shape at the underside where it transitions from vertical to the channel's lower horizontal flange. It supports the channel for ht and allows exact adjustment in and out & side to side, and as well for plumb. Details details.
Crew will likely pop it back out to clean it up and then paint at least the inner face with some epoxy (same epoxy we applied to the square and plate dowels). After the subgrade is straightened via vibe plate, then the reinstall and finish up the balance of the mat.

 

[oceanobob]

Last strip and the dock: concrete placed today.

 

[oceanobob]

Got this room scrubbed and cooled down & occupied just before the 4th.

Will re-visit and install the low mod epoxy on the crack control saw joints in the off season. Diamonds (squares) at columns [appears as darker concrete in pic as was last item placed] have felt joints, those will receive a self leveling polyurethane.

Dock accessory not welded on yet: still on my punchlist. Some painting to do as well.

Pic shows the finished job "in use".

 

[CM1995]

That project turned out real nice Bob!

 

[oceanobob]

We are working at the produce cooler to finish the temp repairs to the loading dock where the existing 8" C channel has fallen almost off. That strap with the four Titen HDs from Simpson held well but the channel was 'walking' when the forklift passed across = nervous lift operators.

Sidebar: The floor is wonderful! I must give credit to the square dowels and the plate dowel. We had a good mix and good curing conditions but west coast aggregate isn't limestone and we get cracks in spite of actions taken to prevent.

~~~
As to the dock repair, we cut sections of the slab and removed the c channels and levelers.

Pics show the reachlift carrying the mini & hammer on and off the dock. Reachlift bucket hauled off the rubble and is now hauling off the extra soil.

Excavated soil to about 5-6" below bottom of concrete, will compact and bring to grade with Class II Road Base. Anticipating a 10 - 11" thick concrete section near edge of dock. Pic of hole by dock 3 not excavated at the time of pic.

How to secure the dock edge C channel? Same as the other one at Dock 2 done when the job done in 2016: approximately 3' long on staggered centers made of welding grade rebars pushed just barely through the channel web by way of rotabroached holes and welded with 7018 inside and outside, then ground flat on the outside. No J bends to make the welds: that typical style of dowels were found under the old channels and had failed by erosion and wear and loss of weld metal. Rebar mat to be double mat: one mat high and one mat low. Bends on end.

Gotta get this done in a jiffy so the produce can be shipped across the country and to the cities! Can you guys see the owl mascot in the pic? Some may think it is a real plastic owl LOL.

 

[Ronsii]

Nice job there oceanobob

We just removed a similar dock but it had plenty of rebar in it...

 

[oceanobob]

when the rebar gets bad and circumstances allow, we have been running the aggressive diamond blades and cut it up in manageable pieces....diamond blades cost vs other costs and is more expedient and predictable. That job looks involved due to the size as well as other reasons. Did you have to change that channel? We always have a hard time with the handheldsaws on a wall horizontal cut and we dont have a wall saw - the saw specialists exact a toll on the wallet for their wall work

 

[hosspuller]

Are they using a jockey truck to move trailers to and from that dock ? I had a problem with bumper pads being ripped or broken away from the dock. Finally figured it was the jockey truck lifting or setting down the trailer while contacting the pads. The trailer acting like a giant crowbar. The solution was steel faced rubber pads. The metal allowed the trailer to slide yet the rubber absorbed the shock of a trailer impact.