Fence post repair.

[peweuk]

I have some wobbly fence posts - not rotten, just not buried deep enough by the contractor - the soil is soft and prone to water retention.

In the past, I have used concrete repair spurs to steady wobbly posts, but where we are there are no merchants within driving distance who sell them, and the only merchants online who will ship want a fortune for the shipping due to their weight.

So I thought about making a mould and casting my own. I have the re-bar to cast into the spurs but I would like to know if anyone has the experience of such a project to suggest the best mix of concrete for use in a mould when making them, and how long they would need to 'cure' for before using them.

 

[JohnD]

If you keep fresh concrete constantly wet for a month, it will reach its design strength.

It reaches 70% after 7 days.

It must be constantly wet. Immersing in water or wrapping in plastic are easy methods.

This is a chemicsl reaction. When it dries, it stops curing and will not restart.

It will be slightly stronger if you can keep it wet for a year or more, but this is not usually practicable. Improvement gets slower over time.

 

[peweuk]

If you keep fresh concrete constantly wet for a month, it will reach its design strength.

It reaches 70% after 7 days.

It must be constantly wet. Immersing in water or wrapping in plastic are easy methods.

This is a chemicsl reaction. When it dries, it stops curing and will not restart.

It will be slightly stronger if you can keep it wet for a year or more, but this is not usually practicable. Improvement gets slower over time.

Thanks for that - I never realised that keeping concrete wet for a period makes it cure more effectively.
What mix would be best (for strength).

 

[JohnD]

As a quick answer, a concrete mix ratio of 1 part cement, 2 parts fine aggregate (sand) and 4 parts course aggregate will cover most general domestic jobs.

I mostly use 1:3 or 1:4 with all-in ballast for small mixes

Use only enough water to let you place and consolidate the mix. It is easy to overwet with small amounts.

There are weight tables for scientific calculation, which I have not got.

A plastic spot board us very handy for mixing such small amounts, and you must turn it so there are no patches of unmixed material.

"Postcrete" is not warranted for strength and is not a normal concrete.

 

[peweuk]

As a quick answer, a concrete mix ratio of 1 part cement, 2 parts fine aggregate (sand) and 4 parts course aggregate will cover most general domestic jobs.

I mostly use 1:3 or 1:4 with all-in ballast for small mixes

Use only enough water to let you place and consolidate the mix. It is easy to overwet with small amounts.

There are weight tables for scientific calculation, which I have not got.

A plastic spot board us very handy for mixing such small amounts, and you must turn it so there are no patches of unmixed material.

"Postcrete" is not warranted for strength and is not a normal concrete.

Thanks for that detailed reply.
There are only 4 posts to deal with, so I can take my time and make sure the job is done properly.

Thanks again.