Question
We live in Arizona and will be having a paver patio installed.  From what I have read it sounds like the base should be  ABC stone base  (one landscaper told me that this was a concrete mix), followed by a layer of concrete sand.  I've asked each contractor what they use as I am getting bids- one uses the AB base and sand, another uses 1/4 minus, and a 3rd told me he uses a mortar sand.  Are these all the same or is there one that is better than the other?   I don't want to have issues of settling/cracking (which we had with a cement patio).

Answer
Hello:

The ABC (aggregate base course,also known as crusher run) does resemble concrete mix and with the addition of portland cement could be used to make a type of concrete. ABC is an excellent foundation base material for paving and is a lower cost material. Go with the most corse sand for the top base.

The corser sand will drain better than a finer grade such as mortar sand and in arizona your paving will be subject to the freeze/thaw cycle. A course of ABC topped with corse sand would make a very good foundation.

The ABC will not achieve the same hardness as concrete and will retain some flexibility and cracking should not be a problem. The ABC compacts very well and that will eliminate settling.

Mark Harshman


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