1. SOIL SHRINKAGE
Soil shrinkage is the most common factor to see. It mainly occurs when the shrinking water decreases in the soil, which causes changes in its pore structure. As the soil dries and the water content decreases, it leads to a reduction in soil volume.
More specifically, the clay soils are susceptible to shrinking more as the mineral composition is higher in them and can retain more water.
Sandy soils, with larger particles, have less water retention and cause less shrinkage. However, shrinkage causes cracks in the soil itself, which causes settling and uneven pressure on the concrete and often structural damage.
2. INCREASED RISK OF SURFACE DAMAGE
When the concrete dries too much, it becomes brittle. In severe cases, the surface of the soil starts to erode, and often the outer layer breaks and gets apart. It is mainly due to the extreme heat and UV radiation exposure on the protective sealants applied to concrete surfaces. The slope crack might widen and can lead to spalling.
Even chemical changes in the concrete surface due to the UV rays make the concrete discolored and bleached. It fries off the epoxy-based sealants and creates holes, which increase the risk of trip hazards as well.
3. FOUNDATION SHIFTING AND SETTLING
During summer droughts, the lack of rainfall causes water absorption, leading to a reduction in the soil volume, often by 10–20% or more. With less water retention, the soil shrinks, contracts, and pulls away from the foundation. All this creates gaps and voids beneath the concrete or slab.
However, as the moisture level around the foundation can vary, some soils in areas shrink more than others. This uneven shrinkage leads to differential settling and foundation movement.
With the heat increasing, the soil becomes harder and more compact, something that leads to soil consolidation. Some of the noticeable consequences include:
- Doors and windows that stick or fail to close properly
- Separation or gaps in brick veneer or exterior walls
- Cracks in concrete slabs, driveways, or patios
- Sloping or uneven floors
4. CONCRETE SLAB MOVEMENT
As a like foundation movement, you can see signs developing in the concrete slab as well, due to droughts. It also results from soil shrinkage and uneven moisture loss beneath the slab. When the clay or the fine-grained soils dry out under the slab, they contract, reduce the volume, and pull away from the slab’s underside.
It often creates gaps where the soil no longer supports the concrete evenly, and slabs start to crack or shift. Even when drought ends and rain returns, the previously dried soil absorbs water, expands, and causes heaving or upward displacement.
5. WATER DRAINAGE ISSUES
In case droughts stay for a longer period, which is common in the midwest region, the concrete develops shrinkage, create gaps, and affect the natural drainage system around the property. In most cases, slopes developed by the shrinkage direct drainage water toward the foundation instead of away from it.
That’s the reason it is common to face water pooling in the summer season near the home, increasing the risk of basement flooding. Even when the drought occurs, vegetation may die off, causing an increase in fallen leaves and debris. This eventually clogs drainage systems, such as gutters or storm drains, increasing hydrostatic pressure against foundation walls.
6. THERMAL EXPANSION AND CONTRACTION
Concrete naturally expands when heated and contracts when the temperature goes down. The average coefficient of thermal expansion for concrete is about 10 millionths per degree Celsius. It means a 30-meter-long concrete slab can expand or contract by about 1.7 centimeters with a 38°C temperature change.
In case this expansion cycle exceeds the concrete’s tensile strength, it forms cracks, which are known as thermal cracking. Uneven expansion causes the concrete slab to warp or chip at the edges. It is especially in pavements and driveways. In the worst case, repeated expansion can even reduce the load-bearing capacity.
