Max123
Well-Known Member
A helical pile, in a boulder field?
Concrete Forming in the intertidal zone
- Thread starter eriks
- Start date
eriks
Active Member
Sorry to hear your news. I was in the same boat a few years ago but was lucky how it worked out. Thinking about you and hoping for the best.
eriks
Active Member
The thread started because I was quoted $25K per screw pile and just don’t have that type of cash kicking around.
Bearded wonder
Well-Known Member
I wouldn’t wet set the block into grout as the blocks are extremely heavy and will squeeze out most of the grout. For most grouts you need at least 3/4” of space. If not it will crack. If you are worried about the blocks rocking I would shim and grout.
Maybe start with 3/4” stainless nuts as a spacer and shim with ss metal strips. Build a quick frame around the blocks and pour flowable grout. Pretty easy.
Or place the blocks and use Sikadur -53CA.
can.sika.com
Sika makes great products don’t use PL. White Cap carries lots of concrete products.
Maybe start with 3/4” stainless nuts as a spacer and shim with ss metal strips. Build a quick frame around the blocks and pour flowable grout. Pretty easy.
Or place the blocks and use Sikadur -53CA.
Sikadur®-53 CA
Sikadur®-53 CA is a two-component structural grout based on epoxy resin, designed for injection, anchoring, and seating applications and for use at temperatures between 5 and 30 °C.
can.sika.com
Sika makes great products don’t use PL. White Cap carries lots of concrete products.
Max123
Well-Known Member
Yowza - thats a big dock post. Seeing the size of that thing I'd definitely connect the two blocks together and might see if you can do a few rods epoxied into boulders underneath - or run a cable from the top of the post and triangulate off two adjacent boulders.
Also - it looks like that post is about 4ft below the high water mark? The reason I ask, is because I suspect the post is sealed on the bottom. Assuming a 0.75m diameter post, 1.2m underwater that creates an air volume of 0.5m3 or about 500kg of buoyancy (flotation will increase if high water mark is higher). You have about 3400kg of concrete lock blocks, so its not going to float way, but it reduces the effectiveness of the lock blocks as a mass footing. Easy solution is to just fill up the inside with gravel or rocks up to the high water mark. You could drill holes as well to neutralize buoyancy, but the galvanizing looks too nice for that. If the bottom is open, disregard my comment.
Also - it looks like that post is about 4ft below the high water mark? The reason I ask, is because I suspect the post is sealed on the bottom. Assuming a 0.75m diameter post, 1.2m underwater that creates an air volume of 0.5m3 or about 500kg of buoyancy (flotation will increase if high water mark is higher). You have about 3400kg of concrete lock blocks, so its not going to float way, but it reduces the effectiveness of the lock blocks as a mass footing. Easy solution is to just fill up the inside with gravel or rocks up to the high water mark. You could drill holes as well to neutralize buoyancy, but the galvanizing looks too nice for that. If the bottom is open, disregard my comment.
eriks
Active Member
For the galvanizing process, you need to provide drain/vent holes, so yes, there are holes in four quadrants at the base, and the column has no cap.
My neighbor has a 48” column on a 6’x6’ footing, with an 8’ wide walkway above. Their first column toppled over apparently, but their current one is good. Our walkway will only be 4’ wide and our column is 36” x .375” wall. Being that size, it’s like having two columns, but with all the debris (logs) in the water here, that’s probably not a great idea and a single large column like this obviously greatly increases the stability.
The blocks were bolted together with galvanized channels. I didn’t grout underneath the blocks. I might try go out there this evening at around 9pm and try reef on the end of the HSS beam and see if there’s any movement. I have to still pack big rocks around the base of the blocks on two sides only, as two sides are up against some rocks. So still some work to do on this. I am keen to see if there’s some suitable areas to epoxy and bolt the blocks down to some of the big rocks next to them.
Max123
Well-Known Member
It all looks pretty skookum. Just thought I'd point out the buoyancy issue if you hadn't thought about it.
If you are concerned about lateral force on the post and risk of overturn like your neighbour - an easy way to significantly increase the robustness of the design is with diagonal cables triangulated off the top of the post out to either side.
Super easy to dowel some 1/2" stainless rod into those giant boulders, add a few shackles and and then run cable up to the beam on top of the post. You can even do the cables in an X configuration behind the post to minimize exposure. Just be careful when you tension each cable that you don't pull the post out of plumb!
PS - Thanks for sharing - I love seeing stuff like this get built!
If you are concerned about lateral force on the post and risk of overturn like your neighbour - an easy way to significantly increase the robustness of the design is with diagonal cables triangulated off the top of the post out to either side.
Super easy to dowel some 1/2" stainless rod into those giant boulders, add a few shackles and and then run cable up to the beam on top of the post. You can even do the cables in an X configuration behind the post to minimize exposure. Just be careful when you tension each cable that you don't pull the post out of plumb!
PS - Thanks for sharing - I love seeing stuff like this get built!
