Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Castling pile cap while driving other piles 4
- Thread starter ebsico
- Start date
Don't have a reference but it makes perfect sense. You don't want high intensity energy waves traveling through your weak, uncured concrete. It would likely cause all kinds of cracking and internal problems, displaced rebar, etc. The couple of days you might save in compressing your schedule (depending on the size of the building, of course) could easily cost you the entire building.
- Thread starter
- #3
As in they want you wait 28 days after driving piles to cast the caps? What kind of piles are you driving?
Where is this written? In the specs? If so, then I'd hardly call it a delay since it would have been part of what the project schedule should have been based on. Have you asked the designer WHY they want you to wait? Pro tip: don't adopt a tone of questioning their decision, let them know that you want to learn more about it. Most engineers have a repressed teacher living inside them just waiting for a chance to show off how smart they are. But also a fierce pride that will get defensive if you challenge said knowledge.
Where is this written? In the specs? If so, then I'd hardly call it a delay since it would have been part of what the project schedule should have been based on. Have you asked the designer WHY they want you to wait? Pro tip: don't adopt a tone of questioning their decision, let them know that you want to learn more about it. Most engineers have a repressed teacher living inside them just waiting for a chance to show off how smart they are. But also a fierce pride that will get defensive if you challenge said knowledge.
-
1
- #5
I'm going to take the opposite side of phamENG on this one.
As a contractor you are obligated not to do anything stupid, which is great, because you don't want to do anything stupid either. In this context, you wouldn't want to drive piles the same day as pouring concrete or even the next day for the very reason phamENG mentioned. However, if the process of driving + concrete capping has resulted in routine success in the past by waiting for the concrete to gain, say 75% strength, then you are not doing anything stupid by following that experience. If that experience is not contra-code (if it was you and the engineer would both be able to point to that) then it is up to the EOR, should they want something different, to put that into the specifications / drawings during the tendering phase or else point to the relevant code.
If the EOR has not done either of those things you are under no obligation to oblige them without being compensated.
EDIT - BTW this has been asked slightly differently previously on eng-tips!
As a contractor you are obligated not to do anything stupid, which is great, because you don't want to do anything stupid either. In this context, you wouldn't want to drive piles the same day as pouring concrete or even the next day for the very reason phamENG mentioned. However, if the process of driving + concrete capping has resulted in routine success in the past by waiting for the concrete to gain, say 75% strength, then you are not doing anything stupid by following that experience. If that experience is not contra-code (if it was you and the engineer would both be able to point to that) then it is up to the EOR, should they want something different, to put that into the specifications / drawings during the tendering phase or else point to the relevant code.
If the EOR has not done either of those things you are under no obligation to oblige them without being compensated.
EDIT - BTW this has been asked slightly differently previously on eng-tips!
Enable - not to split hairs, but I think we agree?
The thing about questioning the engineer was more of a communication tip than a stance on who is right and wrong. It sounds like in this case the engineer has the final say in what you can do. So who is right or wrong is, sadly, irrelevant. What matters is that the engineer has the position of "power" and changing the mind of somebody with "power" can sometimes take a delicate touch if you don't want them to shut you down out of hand.
Typically construction can move forward at 7 or 10 days, or even earlier if you have early breaks to prove strength. Which is why I'm curious about the 28 day comment. Sounds like the OP has cast in place piles rather than driven piles. For driven I'd expect maybe a couple day "set up" period if blow counts or a load test were a little low. Otherwise, if load test is good then why wait at all to cast as long as all the piles are in the ground?
The thing about questioning the engineer was more of a communication tip than a stance on who is right and wrong. It sounds like in this case the engineer has the final say in what you can do. So who is right or wrong is, sadly, irrelevant. What matters is that the engineer has the position of "power" and changing the mind of somebody with "power" can sometimes take a delicate touch if you don't want them to shut you down out of hand.
Typically construction can move forward at 7 or 10 days, or even earlier if you have early breaks to prove strength. Which is why I'm curious about the 28 day comment. Sounds like the OP has cast in place piles rather than driven piles. For driven I'd expect maybe a couple day "set up" period if blow counts or a load test were a little low. Otherwise, if load test is good then why wait at all to cast as long as all the piles are in the ground?
I think we agree about:
1: It would be quite silly to drive piles (or do any vibratory work) next to fresh concrete. In my own line of work (concrete restoration) we have an industry "rule" that you cant chip next to a fresh pour for at least 3 days. But mostly that's a proxy for 75% strength.
2: Communication with those that have ultimate authority and fancy themselves relatively bright, is best done via inception. If they are wrong, and you know it, telling them that they are wrong is a horrible way to accomplish your own end. One must plant their idea in the head of the authority figure so they think that they generated it! As you point out, pretending that you are silly and asking questions so they can explain it to you is a great way to do this.
I think(?) we disagree about:
3: Who holds the power in such a situation. If I am the contractor on a job and the engineer happens to espouse a divergent view about how I should proceed and it is worth my while to push back, then I should and would regardless of how much authority the owner has bestowed upon them. I absolutely agree that tact 1 through 6 should be inception or a similar technique. However, if steps 1 through 6 were to fail I have the ability to go to step 7. Step 7 is the dig your heels in step. So while they might have the authority to direct me to use a particular method (I am not disputing that), I have the ability to charge the owner for it. And since I have the ability to push for compensation, I don't really view it as an appreciable power struggle. It's just more time and money for the owner and more aggravation in all our lives for little reason.
BTW I would say the vast majority of the time disagreements are not worth pursuing and giving the other person the win is just better for all. However, when said view starts to cost real dollars than that no longer applies (or cases where the designer basically wants to play Russian Roulette with will this stand up once we strip it...who knows lets find out!).
1: It would be quite silly to drive piles (or do any vibratory work) next to fresh concrete. In my own line of work (concrete restoration) we have an industry "rule" that you cant chip next to a fresh pour for at least 3 days. But mostly that's a proxy for 75% strength.
2: Communication with those that have ultimate authority and fancy themselves relatively bright, is best done via inception. If they are wrong, and you know it, telling them that they are wrong is a horrible way to accomplish your own end. One must plant their idea in the head of the authority figure so they think that they generated it! As you point out, pretending that you are silly and asking questions so they can explain it to you is a great way to do this.
I think(?) we disagree about:
3: Who holds the power in such a situation. If I am the contractor on a job and the engineer happens to espouse a divergent view about how I should proceed and it is worth my while to push back, then I should and would regardless of how much authority the owner has bestowed upon them. I absolutely agree that tact 1 through 6 should be inception or a similar technique. However, if steps 1 through 6 were to fail I have the ability to go to step 7. Step 7 is the dig your heels in step. So while they might have the authority to direct me to use a particular method (I am not disputing that), I have the ability to charge the owner for it. And since I have the ability to push for compensation, I don't really view it as an appreciable power struggle. It's just more time and money for the owner and more aggravation in all our lives for little reason.
BTW I would say the vast majority of the time disagreements are not worth pursuing and giving the other person the win is just better for all. However, when said view starts to cost real dollars than that no longer applies (or cases where the designer basically wants to play Russian Roulette with will this stand up once we strip it...who knows lets find out!).
I would have thought a couple of days... not 28. Something like this, to be enforced, would have to be a spec'd item, else, an extra to contract.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
- Thread starter
- #9
-
1
- #11
Look, if you are not able to take what I said and coherently argue for an extra as Dik suggests then....well you are too nice a contractor. Get MEAN my man! Naa actually nicer contractors are in short supply and we would do better if more were like that ![[peace]](/data/assets/smilies/peace.gif "[peace] [peace]")
Anyways, there is not likely to be a code that governs this situation. If you want to point to research, take a look at any research on vibrations next to freshly poured concrete (lots and lots out there). This research from WisDOT indicates vibratory effects of driven piles on 3-day old concrete is minimal and offers the recommendation of a 5-day window prior to driving piles within 10ft away.
Anyways, there is not likely to be a code that governs this situation. If you want to point to research, take a look at any research on vibrations next to freshly poured concrete (lots and lots out there). This research from WisDOT indicates vibratory effects of driven piles on 3-day old concrete is minimal and offers the recommendation of a 5-day window prior to driving piles within 10ft away.
What do the contract documents require? 28 days? You can ask for a change, but that's up to the design engineer if 28 days is in the contract documents. A good design engineer will try to work with you, recognizing that they may need to come to you for something in the future. It's a two-way street.
I would suspect that it is not contained in the contract documents... either in the specs or on the drawings. I've not encountered that in over 50 years... but, have just added it to my project notes.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
-
2
- #15
2 days
Permitted peak particle velocity, inches per second = 7.0; Age of concrete at which vibration occurs: More than 24 hours.
Permitted peak particle velocity, inches per second = 7.0; Age of concrete at which vibration occurs: More than 24 hours.
- Status
Similar threads
- Locked
- Question
- Locked
- Question
