The Constructor

Dynamic Cracks vs. Static Cracks: Effects and Repair Techniques

Dynamic Cracks vs static cracks

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Any concrete structure would eventually see cracks and demand proper repair. Nonetheless, one needs to understand the nature of the crack to repair them properly. Generally, cracks are either static or dynamic. The former is primarily aesthetic and may or may not need repair, whereas the latter endangers the structure's integrity and requires adequate repair.

“Cracking in concrete is influenced by the long-term conditions to which the concrete member is subjected. Generally, long-term exposure and long-term loading extend the magnitude of cracks, especially their width, in both reinforced and plain concrete." (ACI 22R-01 2001).

Static cracks develop due to one-time events such as thermal and shrinkage stresses during concrete curing. However, dynamic cracks are due to recurring forces like rapid freezing and thawing cycles, expansive soils, loading of concrete, and thermal changes.

Dynamic Cracks vs. Static Cracks

Environmental conditions and the nature of imposed loads control whether a crack is static or dynamic.

The best strategy to specify whether a crack is dynamic or static is to observe the crack over a period of six months. If the width of cracks increases, they are likely to be active, and the repair work should involve both structural reinforcement and sealing. Static cracks can be repaired with injection and rarely exceed 0.6 mm in width.

Figure-1: Dynamic Cracks in Concrete Slab
Figure-2: Static or Non-structural Cracks


What are dynamic cracks?

Dynamic crack is a term employed to define cracks that are growing over time. It results from recurring forces such as rapid thermal changes, freezing and thawing cycles, expansive soils, loading of concrete, etc.

What are static cracks?

A static crack is a thin or hairline surface crack that commonly occurs in concrete and propagates very slowly. It seems to be unchanging and considered to be primarily aesthetic.

What is the acceptable width of cracks in a concrete structure?

The acceptable width of cracks in a concrete structure is 0.3 cm.

How long does concrete take to crack?

Cracks in concrete commonly start within 12 hours of the finishing process. This time period may vary based on the weather conditions.  

Read More

4 types of cracks in concrete columns are their causes

How to repair active cracks?

What are the causes of a reinforced concrete slab?

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