DIY precast concrete post

[theprinceofdarkness]

I have cast in-situ concrete lintels which turned out to be successful. I now want to cast my own concrete pillar to replace rotten wooden ones in a garden fence. The fence is panels which drop into slots in concrete posts but in the end wall of my garden there is a dog leg which requires two 135 degree posts. The existing setup are square wooden posts with the panel ends just nailed in at an angle.
The posts will be eight foot long and roughly 4inches square, but with the two sides tapering inwards. I was thinking of using two 8mm reinforcing rods and a 1 1/2 : 2 : 2, cement, sharp sand , pea shingle for the mix with some SRBF to give it extra strength and resilience and water proofness.
Any one got any advice?
Frank

 

[JohnD]

The factory ones have four rods so in plan there is one in each corner (actually made of two pieces in "U" shape crossing over at the top)

Rain penetration and frost of the top causes degradation of RC posts, I find it helps to treat (at least) the top with masonry paint.