Effects of Unrepaired Early-age Cracking in Concrete Structure

As engineering consultants, one of the prevalent issues with concrete structures is cracking of the structure whether at the early stage or later stage.

Early-age cracking is a temporary shortcoming that crops up as a result of a faulty design and construction process. Such cracks can be repaired properly if necessary actions are taken on time.

They can lead to many non-structural and structural issues if not repaired properly, for instance, loss of aesthetic appearance of a concrete surface, long-term maintenance, corrosion of steel bars, etc.

Improper repairing processes further exacerbate the issues, which is why the importance of proper repair techniques and suitable procedures should not be ignored.

Effects of Early-age Cracking in Concrete Structures

• Concrete surfaces will lose their aesthetically appealing appearance if early-age cracking is not repaired on time.
• It leads to long-term maintenance issues.
• If early-age cracking is not repaired properly it may lead to water ponding and allow penetration of aggressive substances like sulfate, chloride, and carbonation.
• These harmful substances cause steel reinforcement corrosion and reduce the lifespan of the structure.
• The service of some concrete structures, like roofs and reservoirs, may be affected over time because of early-age cracking.
• Leakage due to early-age cracking in concrete reservoirs can affect the structure's bearing capacity and accelerate fatigue failure.
• Leakage is also detrimental to building users and their property, such as electronic devices.
• Early-age cracking in special functional structures is entirely prohibited because any leakage may result in serious accidents.?
• Special structures include chemical and radioactive waste storage, nuclear containment vessels, nuclear power plants, liquefied natural gas tanks, and waste disposal structures.
• Early-age cracks are common in?concrete pavements, sidewalks, and curbs and lead to unpleasant appearances and costly maintenance if left unchecked (see Figure-1).
• Early-age cracks develop in repair or overlay works in which high early strength concrete is used. This is because this type of concrete experiences high shrinkage. These cracks may compromise the function of the overlay or repair work.
• It raises public concern due to?safety issues. Designers and engineers may argue that early-age cracks do not affect the structure's safety, but this is hard for occupants to understand.

Are early-age cracks considered as structural cracks?

Early-age cracking is a temporary shortcoming of the design and construction process. Such cracks can be repaired properly if necessary actions are executed on time.

The major effects of unrepaired early-age cracking

1. Penetration of aggressive substances into concrete and ultimate reduction of durability.

2. Leakage in water-retaining structures

3. Compromising bearing capacity

4. Occurrence of catastrophic events in case of leakage in chemical and nuclear facilities.

The types of early-age cracking

The types of early-age cracks based on crack characteristics are as follows:

1. Random cracks

2. Map Cracks

3. Transverse cracks

4. Longitudinal cracks

5. Corner cracks

6. Re-entrant cracks

How early-age cracking affect the cost of the structure

Early-age cracking can lead to costly maintenance and increase the structure's cost.??

Why early-age cracking is prohibited in special structures

Early-age cracking in special functional structures is prohibited because any leakage will create disaster for humans and the environment.

Some harmful substances that can penetrate into concrete via cracks

1. Chloride in de-icing and marine slats can quickly reach steel bars in concrete and accelerate corrosion. This corrosion becomes dangerous when it occurs at a single point on the bars, leading to rupture and making the reinforcement ineffective.

2. Carbonation causes a reduction in the high pH of concrete which is the reason for the passivation of steel in concrete. The widening of cracks makes carbonation much faster.

3. When cracks occur and are unrepaired, the concrete's humidity increases, leading to an increase in the corrosion rate of steel bars. In the case of frost, water freezing in cracks widens cracks quickly and causes more severe damage.

Necessary preventive measures should be put in place to check the occurrence of cracks in any concrete structure as this will ensure tethered structures, withstanding all forms of environmental exposure.

Credit: The Constructor