Types of Concrete Cracks

Let us know more about the different types of concrete cracks commonly seen. It is pretty cumbersome to conclude what exactly caused a specific crack. To reduce the appearance of cracks and make a more creatively pleasing concrete project, techniques including site preparation, the most appropriate and suitable mix, and excellent concrete finishing should be in place. Let's now see various types of construction cracks.

Plastic Shrinkage Concrete Cracks

Concrete cracks are seen developed at the time of the construction due to plastic shrinkage on the freshly laid concrete's surface before the same is set. It is when the concrete surface depletes water quicker than the bleeding process the top layer initial shrinkage happens. As the concrete is still in a lucid state and unable to withstand any tension, the concrete cracks appear on the surface. When the water evaporates, it leaves humongous gaps between the solid particles, and thus the concrete becomes weaker, resulting in cracks due to these empty areas. If this type of cracking happens regularly, then the term used is plastic shrinkage cracking. When there is a continuous layer of water on the surface of the concrete, the possibility of developing a crack is nil. 

It is the slab that often develops plastic shrinkage cracks. The concrete slab's surface turns extremely stiff as it dries quickly. As a result, the flow is stopped, and it won't be able to withstand the tensile stresses triggered by restricted shrinkage.

Plastic Settlement Concrete Cracks

Plastic settling concrete cracks develop in freshly laid cement concrete in a reinforced structure, while the plastic settlement cracks develop on the surface before the concrete has hardened and when there is also loads of bleeding. What's more, the downward sedimentation of the solids is also impacted by some type of obstacle, say, reinforcement bars. 

Also, fresh concrete has the propensity to recede or settle when poured into deep formwork like a wall or column. Furthermore, short horizontal cracks will happen if this settlement is slowed by obstructions such as steel bars or big aggregates, resulting in the breaking of the back of the concrete above them. To put it this way, plastic settling cracks are a type of subsidence triggered by a decrease in volume.

Expansion Concrete Cracks

Expansion concrete cracks happens when concrete slabs are exposed to heat. The crack of the slab is caused when they don't have enough space to expand, as the concrete expands and pushes against whatever comes in touch with, say, a brick wall or adjacent slab. The increasing force will likely to lead to concrete crack when neither can flex. As expansion joints are used to separate static surfaces, and as the expansion joints are often formed of a compressible material like asphalt, wood, or rubber, they must act as shock absorbers to relieve the stress that expansion places on concrete and thus avoid cracking.

Heaving Concrete Cracks

Heaving concrete cracks is a temperature-related crack as exposure to extremely cold temperatures causes the slab to condensate, thus resulting in heaving cracks. When the temperature becomes normal, the slab also gets back to its original shape. Heaving cracks can be seen frequently due to this shift in shape. 

Cracks Due To Corrosion of Reinforcement

When the steel gets rusted, it will form iron oxides and hydroxides, which have a much larger volume than the original metallic iron. High radial bursting stresses around reinforcing bars result in local radial cracks due to the increase in volume, while splitting cracks can spread along the bar, resulting in longitudinal cracks or concrete spalling. A prominent issue in bridge decks called delamination might also happen when a broad crack develops at a plane of bars parallel to the concrete surface. When the minor splitting cracks offer free access to oxygen, moisture, and chlorides, it will speed up corrosion and cracking.