Irma....

[zenoahphobic]

Always a difficulty determining an acceptable life of something. Our wall was guaranteed another 50 years ( don't know how they calculated that) through catholic protection.
Far be it for me to say how to construct a wall that can withstand those conditions, but I have observed. When a wall fails it would seem you have plenty of evidence of what has happened, particularly at low tide and after some excavation. We can only judge on a few pictures (excellent they may be)..
It seems critical steel had rusted and failed in the topping and within the vertical panels, these vertical panels have broken some way down but leaving the bottoms vertical and steady in the canal floor.
Leaving the beam aside, it would seem they would have failed on their own, so I hope the replacements are of better life. And as I see it, it was the water behind the wall releasing its weight when the water on the other side of the wall in the canal receeded to its normal or even lower level at that "no water" surge.
This means two things to me. One: the water could not drain quick enough from behind the wall. And two: these panels perhaps should have supports at where they had broken, at some distance down from the top. Because I suspect this level is at the average water height, the zone where greatest corrosion occurs because of the oxygen available above and at a small distance below the waterline. The same principle where steel water tanks rust through at the top, at waterline level, rather than at the bottom where they are always submerged with water.
Just my "civil engineering" thoughts, because not all failed through "age".

[TownsendsFJR1300]

Your correct on most points...

The re-bar, in the old slabs rusted the worst (down to nothing) at the average water line. When the tide went much lower than "low tide", that was the last straw.

With that said, the NEW SLABs, NOW are covered (like the dead man re-bar) re-bar INSIDE the slabs. That should help considerably with corrosion.

[TownsendsFJR1300]

Todays progress:

(Tomorrow retaining walls get formed and poured)

[99yam40]

what did they put under the slab over the water to hold the concrete?
Plywood maybe?

[TownsendsFJR1300]

what did they put under the slab over the water to hold the concrete?
Plywood maybe?

They jetted a couple of posts into the canal bottom and then attached a long 2 x 6 to my lift posts and their "jetted posts". (clearly seen in the pic) for support.

Then a WHOLE bunch of doubled up 2x 4's under that. (sticking out towards the boat).

Plywood then under that, so yes, plywood. That support stays there for a week.

"Overland" forms comes off tomorrow.

I had some extra 3/4" re-bar, (3 about 5' lengths) which I had them attach to their re-bar (extending from land over the water-where the cantilever broke off). Just a little extra insurance. Can't have too much re-bar!!

*BTW, I had to work when they did this back in 1983 so it's the FIRST time I'm seeing the procedure myself.

.

[zenoahphobic]

I think there is an optimum size and amount of reinforcing bar per amount of concrete. Too much steel when heated up can create expansion that will crack the concrete.
Too thick a bar can cause earlier onset of "concrete cancer" , because rusting expands the steel, the thicker the steel the greater the expansion, I would imagine also.
The trick of course, is to totally have the steel buried in the concrete without any of it sticking through, and that that must come out from the concrete, is well sealed.

But as said, this job will do another lifetime, somebody else's worry in the future. Nice to watch work in progress ,the eventual evolving into something useful again, something pleasing about new things,

[TownsendsFJR1300]

Haven't yet, but tomorrow, I can actually get to the boat / lift control box W/O balancing on a 2 x 6" (which was supported by an extension ladder stuck in the canal bottom-IE, not terribly sturdy)!

My little bit of re-bar was attached to theirs, no where's near where water has easy access to (as you can see, they have spacers holding up all the re-bar in the center of pad).

[99yam40]

what are those spacers made of?
looks like pieces of brick or foam maybe.
seems that would be a weak/thin area from the underside of concrete

that rebar does not look coated in the slab

[pstephens46]

what are those spacers made of?
looks like pieces of brick or foam maybe.
seems that would be a weak/thin area from the underside of concrete

that rebar does not look coated in the slab

Maybe coated only where the concrete is submerged regularly.

[zenoahphobic]

what are those spacers made of?
looks like pieces of brick or foam maybe.
seems that would be a weak/thin area from the underside of concrete

that rebar does not look coated in the slab

They should have used specifically made supports of thin rod. We call them " chairs", just strong enough to support not only the mesh but the weight of a person when working with it poured. They may have pulled them out of the slurry as it was poured because the mess stays suspended, but......
I always worry about "tradies" hiding suspect work that can't be seen! Another pet hate is that they leave or hide their rubbish. Had two new Airconditioning units put on my roof, the waste was thrown in my ceiling under the tiles and neatly hidden in the gutters where they thought no one can see! Pride in workmanship is doing things right , as tidy as possible, with minimal impact on the surroundings (understanding the "big picture" ) and cleaning up after oneself. Standards are dropping, and this why I've become anal and do everything myself, and where I can't, I become a real pain in the arse supervisor.

[TownsendsFJR1300]

To answer all three posts above.

On the ground itself, they split small regular bricks and put them under the mesh to hold it up... The plastic over the ground is to keep the ground from sucking all the moisture out of the concrete as it dries..

Over the plywood (extension over the water), yes, they are a coated (vinyl maybe?-not bare steel) metal "chair" that holds the re-bar up off the plywood. So even when done and forms removed, the only thing slightly exposed underneath is the COATED chair..

And no, that re-bar in the base is not coated with anything. Guess because that base/floor rarely see's salt water. The concrete is about 8" "in-land tapering down to 5 or 6".

The vertical slabs have the sealed/covered re-bar inside (can't see it as their already made before they get here) and the dead man poles are covered. The dead-man bars, where not covered, the bent ends are FULLLY engulfed in concrete..

The new cantilever, the form (2" x 6"?) closest to the lift posts, once removed, now leave a 1.5" space between the dock and posts. I'll be cutting some "plastic wood" (same thickness) to fill the gap. Then they'll be a galvanized "L" bracket (about 2" wide x 1.5" thick) bolted to the cantilever and screwed to the post. Keeps any movement to a minimum and helps support the cantilever.

[TownsendsFJR1300]

To answer all the above, the re-bar in the pad is not coated. I guess because the pad rarely see’s salt water. (The old pad re-bar was very much intact where yanked out).

The re-bar inside the SLABS are said to be sealed (can’t see them) and the dead-man bent ends are completely covered in concrete once installed. (Again, those were still fine upon demolition, no rot what so ever)

It is held up (over ground) with bricks cut in half. Over the wood extension, yes, there’s COATED, steel "chairs" that sit on the wood holding the re-bar in the middle of the concrete. The "feet" would be slightly exposed once the forms are gone. Their about 1/4" thick.

The retaining wall and steps should be going in today.. Pic’s to follow

[TownsendsFJR1300]

Yesterdays progress:



The white "H" PVC thing II made up) was set inside. My regular water and re-cycled water lines / faucets (3/4" and 1/2" lines) will NOW
easily slip thru this making later maintenance much easier. Also, NO DRILLING 8" of concrete... 1/4 turn faucets, a bracket bolts above the faucets to hold a garden hose and a cover
bolts over the hose/faucets (to keep the harsh sun off everything.



Still needs concrete finish work (sand finish):

[dray0151]

Wow this looks fantastic! Sure you will love having all this updated and get to use for a long time!

[99yam40]

Are you doing the water lines yourself before they back fill it all?