Pouring Piers with Water in the Hole
Pouring Piers with Water in the Hole
(OP)
I'm working on a project where we are installing concrete piers that are drilled approx 24 - 25' below grade. The drilled caisson portion of the pier has a signficant amount of water in the hole. The contractor would like to pour the piers using the tremie method and pump the water from the top of the hole as the concrete is poured, displacing the water from the bottom up. Is it okay to leave the concrete un-vibrated? I'm concerned with vibrating the concrete and mixing the water in with the concrete. Also, how should the top portion of the concrete be handled, as this will most likely be contaminated with the water? Should this be chipped away to get down to sound concrete?






RE: Pouring Piers with Water in the Hole
RE: Pouring Piers with Water in the Hole
Tremie concrete is placed as a very fluid mix and vibration may not be needed or even advisable. If done properly it is essentially self-consolidating. However there could be some clean-up and trimming of the top of a completed pile that will be necessary. I've had piles and barrettes placed at nearly 200 feet under water/drilling fluid with good results and no vibration. The placing of concrete with a tremie isn't something you want some one learning how to do on your project. If the pipe is withdrawn to quickly or isn't kept charged you can get some pretty awful results. I'd want to see the history and qualifications of the sub performing the work.
regards,
Michel
RE: Pouring Piers with Water in the Hole
RE: Pouring Piers with Water in the Hole
regards,
Michel
RE: Pouring Piers with Water in the Hole
I also have to echo Michael60's comments on having an experienced contractor handle the tremie, if need be. Having a plastic tremie hose backed up with concrete fall into the bottom of a partially placed pier happens more than you would think.
RE: Pouring Piers with Water in the Hole
Without casing, as mentioned above, pumping the water might create conditions of soil instability.
The use of the tremie method works well - sometimes you need to use casing to stabilize the side walls
You don't typically need to vibrate the bottom portions of a drilled pier - usually only the top several feet.
Specify that the contractor provide clear, defined troughs for the water to flow out away from the piers. Then require the upper 3 to 6 inches of the pier to be cut off after partial setting to remove any concrete contaminated with too much water.
RE: Pouring Piers with Water in the Hole
RE: Pouring Piers with Water in the Hole
RE: Pouring Piers with Water in the Hole
RE: Pouring Piers with Water in the Hole