That is not a good look. How quickly can they get that shored?
Are there reasonable alternative load paths for supporting wind loads or (as with most portal frame structures) will a missing column means that part or all of the building will come down like a pack of cards? Propping might not be...
Is the ROV's internal pressure balanced with the external pressure? Is the ROV sealed and a 'dry environment'?
Why do you think the thrusters need to be stronger at depth? The viscosity barely changes with temperature or depth. Seal drag for the shafts may alter, depending on the ROV construction.
As others have identified, very likely to be carbonation, particularly given the age of the building. The problem is only going to get worse over time as more reinforcement will get affected as the carbonated zone deepens.
Be careful about incipient anode effect with localised concrete patch...
I would further investigate the differences between your 14 day cubes vs. 28 day cubes, be it handling, curing, the exact test procedures or whatever. I have several times found differences in how cubes are prepared and tested affecting results. Testing cubes dry or soaked is a significant...
If your 28 day strengths are lower than your 14 day strengths for the same batch of grout, that suggests significant issues with sampling, curing and testing. Do any of these aspects raise red flags to you after talking with and/or watching the sampler and testing lab?
You tend to need a little more cement paste to cover the angular aggregate's increased surface area but otherwise no major problems, provided the angular aggregate is fairly regular in shape, rather than flaky. I don't know the situation in your region but crushed aggregate shape could be an issue.
The table says XAS, Exposed to sea water, Concrete surfaces in contact with sea water.
Table A.13 Limiting values of composition for unreinforced concrete in contact with sea water (exposure class XAS) might apply.
In that environment, I would choose J2 unless you have a reasonable justification to pick a less onerous steel grade (e.g. steelwork within a permanently heated building). What will you do if the heating goes off for a significant length of time?
Generally to check for fill settlement or fill loss. The concrete capping is typically considered to be supported on the fill.
On rare occasions, there might be an earthing point under a pit lid but earthing is commonly directly to the sheet piles.
In my part of the world, a duct bank is multiple ducts in the same duct run as noted by Heaviside1925 but not necessarily concrete encased. Concrete encasement (and reinforcement if concrete encased) is optional, depending on applied loading, duct strength and duct bank cover. We tend to require...
Most of those barriers/ poles look to be cast in situ while the OP refers to mounting poles to precast barriers. The difference is likely to have some effect on the design.
Don't you just need to write a project-specific material specification for this material? Micropile casing shall have minimum 80 ksi yield and weldability shall conform to etc. etc.
I very rarely use American standards, so I may be talking out of my <choose your own>
When I think of soldier piles, I usually think of small retaining walls with steel H-sections and timber planks. In my world, using tubular piles mostly defaults to king pile walls with sheet piling retaining soil between the tubular piles, generally with much larger dimensions (e.g. ports and...
The foundation's similar diameter and depth complicates selecting a non-destructive test method. Some test methods merely indicate the distance to the nearest surface, some to the furthest. Those methods measuring to the furthest surface tend to filter out 'premature responses' from nearer surfaces.
Two dead after a walkway collapse of an aging Italian housing estate.
https://www.theguardian.com/world/article/2024/jul/23/walkway-collapse-naples-le-vele-di-scampia
