1.Plastic Shrinkage Cracks
Plastic shrinkage cracks typically form when water evaporates from freshly poured concrete faster than it is replaced, causing the surface to shrink.
These cracks are generally shallow and mostly occur within the first few hours of placement, especially in hot or windy weather.
They appear as random, short cracks and are often noticed in large slab surfaces.
Although usually not structurally significant, they can reduce durability if excessive and may allow water ingress.
2.Settlement Cracks
Settlement cracks arise when the concrete settles unevenly around obstacles such as reinforcement bars, pipes, or other embedded items.
These cracks tend to be vertical and may extend deep within the slab, following the contours of the obstruction.
Poor compaction or excessive vibration during pouring increases their likelihood.
If left untreated, settlement cracks can undermine the integrity and durability of the structure.
3.Drying Shrinkage Cracks
Drying shrinkage cracks form as concrete loses water after initial setting, shrinking and pulling apart at stress points.
These cracks are more pronounced in long or continuous concrete elements like walls and slabs.
High cement content and insufficient curing practices can exacerbate this problem.
They tend to widen over time and may affect joint stability if not properly managed.
4.Thermal Cracks
Thermal cracks are caused by temperature changes leading to expansion and contraction of concrete.
Rapid cooling or heating, especially in thick sections, induces stress and results in cracking.
They often appear as straight lines and can occur both soon after pouring or years later.
In severe cases, thermal cracks compromise both aesthetic value and structural safety.
5.Structural Cracks
Structural cracks indicate that the concrete element is subjected to excessive load, movement, or poor design.
These cracks are usually wider and deeper, running across or along major stress lines in the construction.
They often require urgent attention as they may signal impending structural failure.
Repairing structural cracks often involves strengthening or redesigning the affected section.
6.Crazing Cracks
Crazing cracks are a network of fine, superficial cracks that appear on the concrete surface after drying.
They are mostly cosmetic, caused by rapid surface drying and inadequate curing practices.
While not impactful to strength, they can increase permeability and decrease surface durability.
Crazing is often visible on slabs and pavements and indicates poor finishing or curing.
7.Corrosion Cracks
Corrosion cracks result from rusting reinforcement bars within the concrete, leading to expansion and cracking.
Chloride ingress, inadequate concrete cover, or poor-quality materials often accelerate corrosion.
These cracks typically track along the line of reinforcement and may show rust staining.
Without mitigation, corrosion cracks can cause extensive structural damage over time.
8.Alkali-Silica Reaction (ASR) Cracks
ASR cracks occur due to a chemical reaction between alkaline cement paste and reactive silica in aggregates.
This reaction creates a gel that swells with moisture, producing internal pressures and cracking.
They manifest as random, map-like cracks and may appear months or years after pouring.
ASR adversely affects durability and can lead to extensive rehabilitation needs.
9.Overloading Cracks
Overloading cracks are a direct result of excessive load or weight placed on a concrete element beyond its design capacity.
These cracks are large, sharply defined, and usually vertical or diagonal.
Overloading often arises due to errors in structural calculation or unexpected excessive loads.
If not corrected, overloading cracks can progress to dangerous levels resulting in total failure.