Learn how to calculate HPC concrete quantity with step-by-step methods, formulas, and practical examples for accurate estimation at construction sites.
What is Hume Pipe Culvert (HPC):
A Hume Pipe Culvert is a type of drainage structure that passes water beneath a road. It consists of RCC pipe that workers lay in a culvert and then surround with concrete encasing (If required).
A minimum 600mm earth Cushion is required otherwise encasing have to do.
assume Given data :
- Length of the culvert = 12.5 m
- Diameter of Hume pipe = 1200 mm (1.2 m)
- Outer Diameter of Hume pipe = 1440 mm (1.44 m. 0.120 mm Collar)
- Invert Level (IL) = 521.325 m
- Ground Level (GL) = 522.141 m
- PCC Thickness = 150 mm
- Slope = 3:1
- Head wall Length = 7.520 m
- GL at center = 522.315 m
excavation quanity for HPC:
Excavation Quantity of Headwall (HPC):
IL = 521.325 m
GL = 522.141 m
Head wall 1st lift depth = 0.650 m
PCC thickness = 0.150 m
So excavation depth = GL – IL + (0.650 + 0.150)
excavation depth = 522.141-521.325+(0.650+0.150) = 1.616 m
Note: Always remember during excavation, minimum 500 mm offset each side of required length must required.
Now Quantity of excavation = L X B X D
Quantity of excavation = (7.520+0.1+0.1+0.5+0.5) X (1.295+0.1+0.1+0.5+0.5) X 1.616 = 35.158 Cum
Similarly Yo can calculate for Opposite side Headwall.
excavation quantity for pipe bedding area (HPC):
GL at center = 522.315 m
IL = 521.325 m
Collar = 0.120 m
Excavation level = 522.315 – 521.325 + 0.120 = 1.110 m
Note: Always remember during excavation, minimum 500 mm offset of required width must required.
Now Quantity of excavation = L X B X D
Quantity of excavation = (12.5-1.079-1.079) X (1.44+0.2+0.2+0.5+0.5) X 1.110 = 32.602 Cum
You can see in given diagram regarding encasing the pipe.
The get better information regarding cement, click on given link.
Types of Cement in Civil Engineering: A Complete Guide
concrete quantity calculation (HPC):
PCC Quantity for Headwall:
PCC for Headwall = L X B X D
Quantity = (7.52+0.1+0.1) X (1.295+0.1+0.1) X 0.15 = 1.73 cum
PCC Quantity for Pipe bedding area:
PCC for pipe bedding Area = L X B X D
Quantity = (12.50 – 1.079 – 1.079) X (1.44+0.2+0.2+0.1+0.1) X 0.250 = 5.27 cum
Headwall 1st lift concrete quantity:
We have the bottom width = 1.295 m
and slope give 3:1
So, Top width of Headwall 1st lift = Bottom width – (Height of Headwall 1st lift x (1/3))
Top width of Headwall 1st lift = 1.295 – (0.650 X 0.333) = 1.079 m
Concrete Quantity = 7.52 X ((1.295+1.079)/2) X 0.650 = 5.80 cum
Similarly you can calculate for Opposite side.
Headwall 2nd lift concrete quantity:
Now, we have the Top width of Headwall 1st lift = 1.079 m
So, Top width of Headwall 2nd lift = 1.079 – (1.440 X 0.333) = 0.600 m
Concrete Quantity = 7.52 X ((1.079+0.600)/2) X 1.440 = 9.09 cum
Now, its time to deduct the pipe :
Pipe volume at head wall area = (π/4) D² h
Volume = (3.14/4) X (1.44)² X 0.840 = 1.37 cum
Concrete Require = 9.09 – 1.37 = 7.72 cum
Similarly you can calculate for Opposite side.
To get better information regarding concrete slump, click on below link.
how to test slump for Concrete: Practical Site Guide
Headwall Final lift concrete quantity:
We have the Top width of Headwall 2nd lift = 1.079 m
And the Top width of Headwall given = 0.400 m
Concrete Quantity = 7.52 X ((0.600+0.400)/2) X 0.600 = 2.26 cum
Similarly you can calculate for Opposite side.
To get brief information regarding Toe wall and Retaining wall, click on below link.
Toe Wall in Civil engineering : A complete guide
what is Retaining Wall and Its Type: Complete Guide
For pipe culvert, follow the mentioned reference.
- MoRTH section 2900
- IRC:SP:13-2022
- IS 458 : 2003
- IS 783 : 1985
Common mistakes made in excavation
- While excavating on-site, sometimes small mistakes can become major problems in the future. For example, failing to provide the proper offset reduces working space.
- Sometimes, the excavation depth does not measure to the correct level, resulting in incorrect PCC and pipe alignment.
- Soft soil or loose material is not removed, which increases the likelihood of settlement.
- Therefore, workers should always use level instruments while excavating and check the IL (Invert Level) frequently.
Importance of Bedding and Alignment
- The most important task in a pipe culvert is proper bedding and alignment.
- If the bedding is uneven, the pipe experiences an unequal load, which can lead to cracks.
- If the alignment is not correct, water flow is disturbed and blockages may occur.
- Therefore, properly leveling and compacting the PCC bedding is important.
When is Concrete Encasing Required?
- Encasing isn’t required everywhere, but it’s mandatory in certain conditions.
- When the earth cushion is less than 600 mm, encasing is used to protect the pipe.
- Encasing is also necessary in high traffic load areas.
- Encasing provides stability to the structure even in weak soil conditions.
- It increases pipe life and improves load distribution.
How to verify measurement on site
- After quantity calculations, on-site verification remains crucial.
- Use a tape and level machine to verify length and depth.
- Check shuttering dimensions before you pour concrete.
- Record measurements for each lift separately to avoid billing errors.
- If possible, ask another engineer to verify for cross-checking.
Quality Control and Testing
- Slump testing is essential when pouring concrete to maintain workability.
- Cube testing is used to verify concrete strength.
- If the strength falls below the required limit, the structure may be unsafe.
- Therefore, testing should never be ignored.
Practical Site Tips (Engineer Level)
- Always check the drawing before starting work.
- When laying pipes, properly seal the collar joints to prevent leakage.
- Backfill layer-wise and with proper compaction.
- Work keeping the water flow direction in mind.
Safety Precautions during HPC Work
- Proper shoring or sloping ensures safety during excavation to prevent collapse.
- Workers should wear PPE such as helmets, gloves, and safety shoes.
- Deep excavations require safe entry and exit arrangements.
- Proper lighting ensures safety during night work.
To get calculated excel sheet for HPC, click on link below.
Conclusion:
Calculating the quantity of a Hume Pipe Culvert is easy if you follow a step-by-step approach. Correct excavation, PCC, encasing, and lift-wise calculations ensure accurate estimation and minimize material wastage on site.
