News flash, your building’s concrete foundation is vulnerable to cracks, and these cracks are highly dangerous to everyone in your building. Even with the best floor designs and proper construction, over time, your concrete floor, pillars or walls will not remain crack free.
Why is that? To answer this question, we will have to look at the 7 common types of concrete cracks.
Types of Cracks
Plastic Shrinkage Concrete Cracks
Plastic shrinkage concrete cracks occur when an excessive wet concrete mix is used during the construction stage. While a concrete mix does require a certain quantity of water, an excess amount will lead to the slab shrinking more than planned.
This happens as concrete does not immediately harden when set. Instead, when in its plastic state, it is full of water. When the water does evaporate, it leaves behind voids between the solid concrete particles. Empty spaces created in this fashion make the concrete structure weaker and prone to cracking.
Plastic shrinkage cracks are characterized by their narrow width and barely visible nature. Furthermore, they can occur below the surface, extending throughout the thickness of the slab. In particular, they frequently emerge at reentrant corners or with circular objects that are surrounded by the slab. Since concrete cannot shrink around corners, stress can cause a crack to occur form the corner.
Expansion Concrete Cracks
Hot weather causes any material to expand as molecules start to inactivity. Once material expands, it pushes anything that it is in contact with. This includes adjacent structures or slabs. If no space exists for the slab to grow into, the expanding force may potentially be sufficient to cause the concrete to crack.
Heaving Concrete Cracks
Heaving concrete cracks refer to cracks that happen when an upward force pushes up against the concrete from below. Common cases of this happening include large tree roots being located too close to the slab. In this event, there is a risk whereby the growing roots may lift and crack the concrete surface.
In colder environments, the ground movement created by a freezing and thawing cycle can lead to the concrete being lifted several inches. If the slab does not move freely with the ground, heaving concrete cracks may occur.
Settling Concrete Cracks
Similar to heaving cracks, settling cracks occur due to ground factors beneath the concrete slab. In this case, if there a void is created in the ground beneath the concrete with the soil not being compact upon refill, then settling cracks can happen. Common cases where settling cracks occur include the removal of large nearby trees or the digging of trenches for the laying of lines and pipes.
Overloading the Slab
Just like any other building material, concrete does have its own weight bearing limits. If excessive amounts of weight were to be placed on top of the concrete slab, concrete cracks will emerge.
Crazing cracks appear when the top of a concrete slab rapidly loses moisture. As a result, very fine cracks appear, resembling spider webs or shattered glass. While visible, crazing cracks are not a structural concern.
During the concrete stamping process, a method of adding texture or patterns to concrete surfaces, crusting cracks can be formed. If the surface of the slab is exposed to excess sunlight or wind, then the top layer of the slab may dry out quicker than the bottom. At which, point, the top layer becomes crusty. When the stamp is embedded on a crusty surface, it pulls the surface apart and causes small cracks around the outer edges. Similar to that of crazing cracks, crusting cracks are not a structural concern.
It is difficult to determine exactly what causes a particular crack in your building’s structure. Professional site preparation, quality concrete mix and good finish are some of the must have practices towards minimizing the chances of cracks forming.
In the event that cracks do appear, it is imperative that you get a professional concrete repair company to assess the damage, danger and course of action to be taken. Leaving cracks unattended and undiagnosed could lead to severe consequences in the near future.