Cracks in concrete: causes and repair methods

Causes of crack growth in concrete floors

In warehousing logistics, production halls and open areas, the defect is particularly frequent: dynamic loads from reach trucks and forklifts, point loads from shelving, moisture, temperature fluctuations and joint irregularities create the conditions for crack development.

The practice of tConcrete engineers shows: correct work with cracks requires a systematic approach - diagnosing the causes, classifying the defect and selecting the right restoration technology.

Main types of cracks and mechanisms of their formation

1. Shrinkage cracks

Formed during the early stages of concrete curing when there is intense moisture loss.

Signs:

• fine mesh;
• shallow in nature;
• minimal impact on load-bearing properties

2. temperature cracks

Occur due to expansion/contraction cycles of concrete during temperature fluctuations.

Signs:

• considerable length;;
• seasonal variations in opening width;
• are related to irregularities in the operation of temperature joints/li>

3. cracks from operational stresses

Appear when design loads are exceeded or reinforcement is insufficient.

Signs:

• can be profound;
• sometimes run the full thickness of the structure;
• are potentially dangerous.

4. cracks from corrosion of reinforcement

Formed during the early stages of concrete curing when there is intense moisture loss.

Signs:

• vertical or diagonal lines;
• signs of corrosion;
• high risk of further deterioration.

5. Technological cracks in the joint zone

Formed when expansion joints are not properly constructed or operated.

What do you need to determine before repairing?

Correct engineering diagnostics include determining:

1.Causes of occurrence
Without addressing the root cause, the repair will be temporary.

2.Crack depths

• surface → localized filling;
• deep → injection technology or special formulations.

3. opening widths

• up to 0.2 mm is a cosmetic defect;
• 0.2-0.5 mm - firm filling is required;
• more than 0.5 mm - design defect.

4. Crack Dynamics

• stable - doesn't change;
• active - increases under load;
• temperature - varies seasonally.

Cracks in open areas

Outdoor concrete pads work in harsh conditions:

• freeze/thaw cycles;
• exposure to water and salts;
• thermal expansion;
• direct sunlight.

Cracks on the street are usually long, deep and "alive". Frost-resistant and elastic materials are used for their repair.

Cracks in the interior

Warehouses and workshops are characterized by:

• dynamic loads from machinery;
• Stress concentration around the racks;
• temperature fluctuations near the gate;
• stitch malfunctions;
• localized defects during concreting.

Materials

The choice of composition depends on the type and nature of the defect:

1. epoxy formulations

For stable, dormant cracks.
Pros: high strength, excellent adhesion, load resistance.
They are used in industrial floors.

2. Polyurethane formulations

For "live", dynamic and temperature cracks.
Pros: high elasticity, resistance to vibration and expansion/contraction cycles.
They are used both indoors and outdoors.

3. Repair mixtures

They are used for wide and shallow defects, restoration of surface geometry.

4. injection systems

For deep or structural cracks. Options:

• epoxy - restoring strength;
• polyurethane - working with moisture;
• acrylate - filling microcracks.

Stages of crack repair

1. Crack opening

The wide opening allows weak concrete to be removed and quality fill to be provided.

2. cleaning
Removal of dust, cement milk, contaminants.

3. Priming

It is performed on weak and porous substrates.

4. Filling with composition

The choice of material is by type of crack.

5. Leveling and grinding

Critical for industrial floors with high leveling requirements.

6. Control in dynamics

Engineering evaluation of crack behavior after repair.

Dangerous cracks: when engineering expertise is required

Critical defects are:

• with a width greater than 0.5 mm;
• running through the entire thickness of the slab;
• actively increasing;
• with signs of corroded fittings;
• accompanied by subsidence or floor level differences.

Such cases require the involvement of engineers.

Why it is important to repair cracks in concrete in a timely manner

If you are looking for ways to reduce costs in the construction and operation of your facilities, contact the tConcrete team

We look forward to receiving your application. You can share your resume, portfolio and cover letter at hr@tconcrete.ru or send your project to hello@tconcrete.ru