Any construction engineer in the house? I need technical info on how to make durable concrete posts for fencing:
What size twisted bars should I use?
What is ideal concrete mix?
Is it possible to do it at home and save money. I need 200 posts.

Tried this sometime back. Did 50 of them using y10. Normal mix.

The horror for me was after i put them into the ground and left them in for three days; i returned to find scrap metal thieves had brought them down, crushed them and stole the metal...in Katani when it wasnt as developed as now.

still suspect they are part of a house nearby.....

Cost difference when using treated wooden poles (the green ones)?

Oh my goodness. I had not thought of people stealing the chumas. I was obsessed with people stealing the wooden posts for firewood. Now what? I guess one has no other option but to use the flimsy plastic ones!

Not a construction Engineer but i did my research with the roadside guys along outering road, Kariobangi and KAPA Mombasa road last year.

The concrete mold you can have it made for you at 8K-11K per mold by the Juakali guys. Metallic mold is advised as the wooden one takes in moisture and wouldn't last i.e if you intend to be making the concrete posts for years to come. 3 Y8 bars per post is what they use to reduce costs, but i have seen posts with 4 bars which i guess results in more strength of the posts.

Depending on strength required/finances you can use 1:3:6 or 1:2:4 ratio for cement:sand:ballast.

Ballast size is your normal ballast used for construction, i believe 3/4 inch. To give the posts a smooth finish they will mix the concrete mixture with the very fine ballast (they call it dust). Was strongly advised to use ballast crushed by machine and not those ones done manually because you need an even size ballast (3/4 inch).

So that the concrete doesn't stick to the molds you will need oil to apply before pouring the concrete mixture into the molds.

One mold can do 3 posts per day if you push it i.e one very early in the morning, another at around 1p.m and last one late evening. Be careful on the curing time because if not done well they will get cracks soon after.

1 bag of cement will give you 3 posts. 1 post at the roadside will go for around 1,800/= (last year price). If you need to transport these posts your cost goes up so depending on your quantities your may decide to make on site or buy.