To set this tower crane base we need to layout form and pour piers to support the pedestal section of the tower crane base. The pedestal needs to be 24" below the top of footing and this footing was 48" thick so our piers were 24" tall. The bottom reinforcing ran through the piers. So our sequence was to form the footing, place the bottom reinforcing then layout, form and pour the piers before the top reinforcing was placed.
Tower crane base install.
A couple of weeks ago, Constructorator's blog post was on sequence. I thought I would give my two cents on the matter, because it really hit home and it's something I continually preach. Proper sequencing is crucial to every phase and task you and your crew perform. I am also a firm believer in open communication between everyone involved in the task at hand. I really push for input from my crew and any other subcontractors affected when planning sequence.
My current job is supervising two of the four concrete core walls, 83 feet in height. We used a gang form on a rollback system to pour six lifts of an H shaped wall and a rectangle stair core wall. Sequence was the first thing on my mind when pre-planning this job.
I started with the overall sequence by asking these questions:
• Which wall went first?
• How would this affect the ironworkers?
• How many crane picks were we on each wall?
These were a few of the variables that went into the overall sequence plan to create flow. If we didn't plan our sequence and just went at it, we would never meet our tight schedule and budget. The crane time was our biggest obstacle; we had one crane to feed four walls, twenty-five guys, and the ironworkers. If we were out of sequence, we could halt production by needing to jump panels and fly rebar on all four walls at the same time. All of the key players sat down together to come up with a plan that would keep everyone in the proper sequence.
Now that we had our overall plan, we didn't stop planning there; next, we looked at all of the steps we needed to take to pour our walls. Would we gain anything by doing one step before the other? My foreman and I walked through everything together to come up with a plan. We then communicated our plan and opened a discussion with the crew for their input during evening huddles. You would be surprised how processes will improve, if you allow the workers doing the actual work, have a say in their procedures. They might see something that you haven't thought about that could save valuable time.
You should always look to improve process. No matter how good your crew is at a job, there is always room for improvement. Pre-planning sequence should be your first step in helping improve your crew’s productivity.
Why are pre-pour checklists so important? Like anything else, the more planning the better the results right, so why wouldn’t you invest in a solid verification and checking procedure to ensure your next concrete placement is right. If you currently don’t have a pre/post pour checklist then you have to ask yourself how much money is wasted because improper lighting, wrong mix design, slump, spacing, manpower etc. the list can go on and on.
If you have a process for your pre-pour checklist and if it looks something like this
1. Fill out after the pour is already complete
2. Fill it out 5 minutes before the pour
3. Left blank
4. Don’t have/use one.
Then you need to re-evaluate what a good pre-pour checklist can accomplish.
It’s not the signing or the input or even the pre-pour sheet itself that makes a pour card effective. What makes a pour card effective is the process you develop when you go through the checklist. You've seen the best superintendents out there, they are constantly looking and asking when’s this going to be done, we need to set this up… or what about that? They have a pre-built checklist in their head and know all the steps needed for the pre or post pour.
A proper pre-pour process will take you through all the steps and the: Who, What, When, Where, How”.
Who: has verified, inspected, checked, and figured: yardage, elevations, sleeves, anchor-bolts, embeds, reinforcing, elevations, mix design etc.
What: is being placed, size of pour, manpower needed (footing, wall, column, SS, SOG, S.O.M.D)
When: is the pour happening (Date, Time, truck spacing)?
Where: (Placement location, pump truck setup, truck route, wash out bin)
How: is it being placed (pump, screeds, equipment, lighting, safety, etc.)?
The pre/post pour cards are a simple check and verifications. When a thorough examination and paying special attention to detail as well as going through all the steps to checkoff is done, not only will this save you time, money and re-work, but help you plan and execute a successful pour.
Here is an example of a finisher pre-pour card example, like we talked about you just have to create that process to capture and ensure all areas that need checked and verified for a pour have been completed to ensure a successful pour out. If you would like a custom pour card form or need help getting one set up email me at firstname.lastname@example.org
I don't know how many times I have caught myself out of sequence and kicked myself in the butt because I knew if I had thought through the process I would of caught it. Knowing the right sequence in construction will save you time, energy and re-work, but you have to know what to look for and plan it.
First what's the main task: Pour Footings. But when you start looking through the details and notice anchor bolts with 16-bolt pattern and 1-1/2" plate top and bottom along with added rebar stirrups throughout. Knowing this will change your install sequence to work with the reinforcing.
Ask yourself what steps are needed to pour footings?
Now that you have a simple outline of the steps needed to complete the task break it down.
What needs to happen for the excavation?
What needs to happen for the Formwork?
1. Excavation Complete.
2. Layout formwork.
What needs to happen for the Rebar?
1. Formwork and grades established.
2. Anchor bolt-working slab poured.
3. Anchor bolts installed.
What needs to happen for the Anchor Bolts?
1. Working slab poured.
3. Support installed for templates.
4. Reinforcing around bolts.
So your sequencing should be:
1. Layout the hole, get the dirt contractors to X-out the footing.
2. Layout the footing for carpenters.
3. Carpenters form footing and establish grade.
4. Working slabs for anchor bolts poured.
5. Anchor bolts installed with bottom template only.
6. Reinforcing installed.
7. Anchor bolts top template installed.
8. Final check, inspection.
9. Pour Footings.
It does not have to be difficult; it can be as simple as you make it. However, it takes planning and coordination in order to be successful. So take the time and put the effort in, then enjoy the payoff of creating a nice workflow for your crew.