Does the moisture content of the soil in a footing hole affect how bagged concrete cures? Concrete Construction Editor Bill Palmer was asked to answer that question in a recent article for sister publication Journal of Light Construction. The answer depends on variables including type of soil. Additionally, he notes:
Other important factors to consider with soil types are how much the soil will compact and settle with loads placed on top, and whether the soil will expand as it absorbs moisture, as with some clays. If you have doubts about the bearing capacity of your soils, be sure to check with an engineer.