Concrete floor cracks can be a sign of a weak foundation or poor soil conditions, but they can also be repaired relatively easily. Before you decide to pour new concrete over your cracked concrete slab or use epoxy sealant to fill it up, consider these factors:

Concrete is porous and absorbs moisture from the ground below it. If the soil beneath your slab is too wet or too dry, then cracks will form in the surface whenever water freezes and expands. This occurs most often during cold winters but can also happen when temperatures change quickly by heating systems that use steam in their pipes because that causes condensation on surfaces when steam turns into water vapor again (like how your windshield fogs up when you turn off your car engine).

A crack in your concrete floor can be the result of a wide variety of causes, including poor soil conditions, heaving, and constant freeze-thaw cycles.

A crack in your concrete floor can be the result of a wide variety of causes, including poor soil conditions, heaving, and constant freeze-thaw cycles.

If you live in an area where freezing temperatures are common or if you have installed an uninsulated slab on top of poorly compacted fill material such as sand or clay soils (which expand when wet), then it is likely that your concrete will experience some sort of cracking due to frost heave.

Concrete slabs that have been poured over grassy areas will also experience similar problems as those mentioned above because grass roots will grow into the cracks and expand when wetting rains occur during winter months; this expansion will cause further cracking throughout your home's foundation walls and floors

Concrete is a very hard material, and it doesn't like to be moved. Concrete has a high coefficient of expansion and contraction, which means that when the temperature changes it will expand or contract depending on how much heat is applied. Concrete also cracks when it freezes and thaws regularly, so if you live in an area where this happens then you may want to consider using asphalt or pavers instead of concrete.