Having a bored-pile inspection checklist during constructing cast-in-situ concrete piles will ensure the quality of piling work.
In this post, you’ll learn what you actually need to check during bored cast-in-situ concrete pile construction.
In fact, I check these points every time during pile construction.
So, without further ado, let’s discuss what I check to maintain the quality of piling work
Bored Pile Inspection Checklist
I check the following 16 things.
1: Diameter Of The Chisel
The chisel is used to dig the borehole.
The first thing you need to check is the diameter of the chisel.
For example, you are going to construct a 24 inches dia pile.
For that, you need to use 22½ inches diameter of a chisel.
That means the chisel’s dia should be 1½ inches less than the pile dia.
It’s essential to maintain the borehole’s dia.
Checking a chisel diameter is simple. You just need to measure the perimeter of the chisel and divide that with pi (ℼ) to get the dia.
2: Length Of Temporary Casing
The temporary casing is used to prevent falling the loose soil of the top layer into the borehole.
There is no hard and fast rule for the length of a temporary casing.
But you need to make sure that it protects the top loose layer of soil.
We normally use 12 feet long temporary casing.
You can check the length of the temporary casing with a measuring tape.
3: Inside Dia Of Tremie Pipes
Tremie pipes are used to pour concrete into the borehole.
We make sure that the tremie pipe dia isn’t less than 8 inches.
You can check this with a measuring tape.
4: Pile Position
We mark all the pile points on the ground before starting the pile construction.
After starting to bore the hole, you can’t locate the pile point.
So, it is better to keep reference points to check the pile position later after starting boring.
Keep four points around the pile point.
So that you can check the pile point whenever you want.
5: Check The Vertical Position Of The Chisel
We hang the chisel above the pile point that we are going to construct and throw some water on the chisel.
If the water dropped on the pile point, we understand that the chisel is aligned with the pile point.
6: Driving Fluid
We use bentonite as a driving fluid to protect the bore hole’s wall from breaking down. There are many other functions of bentonite.
At this point, you just need to make sure the bentonite is being used during driving.
Related: Uses of Bentonite in Construction (The Constructor)
7: Verticality Of The Bore Hole
It sometimes happens.
After driving some length, the chisel can be shifted from the center point.
But the borehole should be vertical.
You can check this visually – looking at the boring bit.
If needed, you can also use a sprit level.
8: Bore Hole Length
Borehole length is specified in the drawing.
You need to bore the hole up to that length. Let’s say, a borehole is specified as 100 feet long in the drawing.
We generally measure boring bits and mark a point on a boring bit at 100 feet with red color.
Doing this, you can easily get the length of a borehole.
9: Lap Length
When a pile is longer than a full-length steel bar, you need to provide laps.
Make sure the lap length is as specified in the drawing.
10: Concrete Cover
The concrete cover is essential to protect reinforcing bars from corrosion.
It is normally maintained using concrete blocks.
Generally, 3 inches of concrete cover is provided for pile reinforcement.
You can get this information from the structural drawing.
Make sure the concrete cover is provided as specified in the drawing.
You can check this using measuring tape.
11: Placing Tremie Pipes
While putting tremie pipes into the borehole, make sure the bottom end of the tremie pipe reaches till the end of the borehole.
As you have the length of the borehole, you can easily check this by measuring tremie pipes.
12: Bottom End Position Of Tremie Pipe Within Concrete
While pouring concrete, make sure the tremie pipe remains at least six feet inside the concrete.
13: Concrete Slump Test
As you know, the first poured concrete will come up to the top of the borehole.
But pouring pile concrete takes time. Within that time period, the first poured concrete should remain in the plastic state.
You can use chemicals for this purpose.
We normally maintain 6 inches slump for pile concrete.
Related: All About Concrete Slump Test
14: Interruption Of Concerning
Pile concreting shouldn’t be interrupted. Make sure you have an alternate option to continue concrete pouring.
15: Concrete Cylinder Specimens For Testing
We normally make three numbers of cylinder specimens for testing. Make sure you make that.
16: Top Level Of Concrete
The top-level of concrete in the pile should be above 3 feet of the cut-off level.
Make sure it is maintained.
You can check this using a bamboo.
I normally keep a bored pile inspection checklist with me when I go for inspection.
You can do so.
Write each point in a paper and keep that with you during piling work. So that you don’t forget anything to check.
Now It’s Your Turn
Did I miss anything in this checklist?
Or do you want to add anything?
Please do that in the comments below…
To maintain the concrete quality buy Concrete Inspection Guidelines.