When talking about soil compaction, it is often confused for consolidation. Both involve a very similar action that leads to a similar result, though the contents involved are different. When trying to understand why your concrete would settle, it’s important to know how to differentiate the two.
Concrete settling may not be something homeowners can fully avoid, but it is something they can prepare for. Clearing up any misconceptions about how it happens helps with prevention methods, as well as planning when it’s time to fix the concrete.
Compaction
Compaction is the displacement of air in soil due to pressure. When soil is loose and separated, there is a lot of air between each particle. When the soil is pressed together, the particles unite and the air gets pushed out. It depends on the soil, but some soils stay densely packed together when compacted, while others come loose once more.
Clay-rich soil, which is commonly used, compacts really well. Not a lot of pressure is needed in order for the air to be displaced. While this has many advantages, it also means that settlement is common. Alongside shrinkage, compaction is a major cause for concrete sinking.
Consolidation
Consolidation is similar to compaction in the sense that it involves applying pressure to displace an element in soil. However, while compaction is the displacement of air, consolidation is the displacement of water. The water between each soil particle pushes the soil apart, but it all comes together if the water is displaced. More pressure needs to be applied when soil is being consolidated because water weighs more than air.
Just because water is displaced doesn’t mean it evaporates. The water flows down to the next layer of soil. Consolidation spreads moisture to a larger area of effect. The only way the moisture can be stopped from spreading too far is if it reaches soil too dense for the water to go through.