Cement quantity for privacy fence posts

Hello,

how much cement do I need for my 25 holes for a 2 m high privacy fence. The drilled holes currently have a diameter of about 20 cm and are about 45 cm deep. That would be a volume of 0.014 cubic meters.

According to the statement from the hardware store, I need about 50 kg of cement per hole, so a total of about 30 bags.

That seems like a lot to me. Is that correct?

Thanks and regards,

downundaman

On the cement sack it says 20 kg/sqm per cm layer thickness. The hole is 0.1x0.1sqm*pi=0.03sqm. That means at about 33 cm height I would have one sqm. The hole is about 1.5 times higher, so 20 kg * 1.5 = 30 kg.

Still a lot, but sounds more realistic, right?

I always calculate with 2kg per liter. The number of liters is the product of height times width times depth, each measured in decimeters. So here approximately 2x2x4.5=18L equals 36kg. Slightly less because it's a circle, not a square (minus 20%), so that is about 30kg.

Eh, a hole with a diameter of 20cm? What is that supposed to accomplish?

Not only the hole diameter makes me suspicious, but also the depth for a 2 meter high fence.

The foundations are, in my opinion, clearly too small, the wind pressure should not be underestimated.

Diameter 25 cm
Depth 80 cm (frost protection)

Concrete / sand mixture 1 : 3 (better safe than sorry)

I have founded about 50 posts this way and all are still holding.

During the last storm, some fences were knocked down in our construction area...

good luck

Skippy