I did this work in western Canada for ten years and have never seen a rig or process like this. Lots of caisson, rock sockets in limestone bedrock or expanded base but this was $out interesting process to watch
If you notice the concrete mixer trucks standing by, and then after the auger reaches the bottom it stops, and you see the large diameter hose going to the top of the auger jerking and flipping. That hose is connected to a concrete pump, and so once the hole is bored and the soil removed by the internal auger system, the concrete is pumped in to fill the hole and inside of the auger, so that as the auger is pulled out, there is no danger of the sides of the hole collapsing (which in that sandy or silty wet material would just flow right into the unsupported hole). So when the auger is removed that slurry that you see flowing out the end is the concrete that has been pumped in the hole already. Then the rebar cage is lowered into the wet concrete, and it is done. It is very clever, and pretty much the only way to do it in unstable or wet soil conditions like that.
@@26jori similar. Usually what I have seen underwater in mud or sandy bottom is that they drive a pipe piling in, and then use a water jet and suction system to empty the sand and silt out of the pipe, and then run a hose all the way to the bottom of the pipe and pump special grout in from the bottom, which displaces the water above it. For applications like bridge piers and such, they may drive sheet piles around the perimeter of the pier, use dredges and underwater blasting to excavate the footings if there is bedrock, and then pump the grout to the bottom and use the sheet piling as a form for the concrete. For underwater use, the cement used is made with special properties so that it doesn't get weakened by being under water, and is carefully pumped in so that it doesn't get turbulent and mix with the water, but it is very similar to this method.
I'm surprised the concrete/grout would let the rebar settle into it. I would have expected something like a polymer or bentonite slurry to be used first, the rebar lowered in, and then the concrete injected to displace the slurry.
Robert Szasz I think that is actually what was seen. That didn’t look like competent concrete at the top of the shaft. Probably just didn’t film the next step of installing a tremie pipe and placing the concrete.
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The drill has an internal auger, and you can see it coming out the top of the drill assembly, falling through the telescoping ejection tube into a pile next to the hole, where an excavator pulls it away. Then concrete is pumped in through the large hose you can see at the top of the machine, and the auger is then removed. The concrete has to fill the hole before the auger is removed, to prevent the hole from collapsing since that is wet sandy soil and would just flow or slump in. Then the rebar is lowered into the concrete filled hole.
@@ke6gwf I'm in construction, I know how it works, I've put up 90' light poles that needed 36" x 25' hole drilled, they pull up a hell of a lot more dirt than is next to that auger, I see the excavator removing dirt, but it must have removed a hell of a lot more than they show.
@@ke6gwf I think 36" was biggest we ever did, I've probably done hundreds of 18"-24" for parking lot lights, that sonotube is some great stuff. I have a funny story, we were drilling a 20" or so hole for a parking lot light, we start smelling gasoline, we figured it's coming out of the truck, it turns out it's coming from the hole, the dirt in the bottom of the hole was saturated with gasoline, I find the superintend of the job and tell him expecting him to flip out, he just calmly says don't worry about it, I say you don't get it, the site used to be a gas station that actually worked at as a teenager, the tanks must have leaked, he tells me don't worry about it, just fill it with concrete, I was about 24, this was my first big job as an electrical foreman, it was a four story building, I didn't want make waves on my first job, so I did what I was told and filled the hole with concrete. They may have gotten away with it, but the plans called for a small pond with a fountain about 100' from where I hit the gas, I guess eventually gas started leaching into the pond, they ended up having to put some kind of contraption that somehow sucks the gas out of the dirt, it was half the size of a shipping container, they put it right next to the pond in front of this beautiful new building, that was 1984, and that thing is still there.
Then they will poor ciment into mud , I don’t think it will go down to bottom of the pile. As the ciment will flow down , it will mix with the mud , humm good ciment , first quality...
