Concrete fence post repair or installation can take a lot of time and effort. I recommend using Sika PostFix. This is a two-component, mix-in-the-bag expanding foam that I’ve been using on my projects. Two bags of concrete can be replaced with one bag of Sika PostFix. It’s also very easy to use and sets quickly —saving you both time and money. It's also great for DIYers! Sika Canada Inc. | Mike Holmes