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2 Common Types of Cracks in Concrete – How to Prevent?

Despite being a flexible and long-lasting building material, concrete is susceptible to developing fractures over time for a number of reasons. For diagnosing and addressing ethically related problems, it is crucial to understand the common types of cracks in concrete. We, at Firstchoice Readymix, are here to assist you in identifying the root causes and preventing them at an early stage. We can help you have complete quality control over the materials and craftsmanship and increase the lifetime of the concrete construction by elaborating on each source of cracks in concrete. Here are some of the most common types of concrete cracks and their causes:

1. Plastic Shrinkage Cracks:

Plastic shrinkage cracks in concrete occur during the early stages of curing, typically within the first few hours after placement. These fractures appear when there is a rapid loss of moisture from the surface of the concrete, causing it to shrink and crack. Several factors contribute to the development of plastic shrinkage cracks:

Hot and Windy Weather:

The evaporation of water from the concrete's surface is sped up by hot, windy weather. Rapid drying causes the surface to shrink, which can cause tensile strains and breaking. Low Humidity: The pace at which moisture is lost from the concrete surface can be accelerated by low humidity levels in the surrounding area. Plastic shrinkage cracks are more prevalent in arid or dry areas.

High Concrete Temperature:

The surface may stiffen and break before it has a chance to properly consolidate and cure if the concrete mix is too hot when it is poured.

High Water Content in the Mix:

Due to the extra water that must evaporate, concrete mixtures with a high water-to-cement ratio are more prone to plastic shrinkage cracking.

Inadequate Curing:

For plastic to avoid cracking due to shrinkage, proper curing is essential. The surface may dry out and fracture if concrete is not properly cured or if curing is delayed.

Lack of Windbreaks:

Inadequate windbreaks or shadowing over newly poured concrete can worsen moisture loss and increase the likelihood of surface cracking.

Non-Uniform Curing:

The uneven distribution of moisture over the concrete surface caused by inconsistent curing techniques, such as partial shade or unequal application of curing agents, might encourage cracking.

High Cement Content:

Because high cement content concrete mixes produce more heat during the hydration process, which might hasten setting, they may be more susceptible to plastic shrinkage cracking.

To prevent plastic shrinkage cracks in concrete, it's important to take the following precautions:

Use Proper Mix Design: To reduce excess water content, the concrete mix should be designed with a suitable water-to-cement ratio. Use Superplasticizers: Superplasticizer admixtures reduce the setting time and promote better consolidation in hot conditions. Use Sunshades and Windbreaks: Especially during hot and windy circumstances, provide shading and windbreaks to shield the concrete surface from direct sunlight and wind. Start Curing Early: After completing the concrete, start curing as soon as you can to maintain moisture on the surface and stop moisture loss from happening quickly. Apply Curing Compounds: To maintain moisture levels during curing, apply curing compounds or cover the concrete with damp burlap, blankets, or polyethylene sheets.

2. Overloading Cracks:

Cracks in concrete due to overload, often referred to as overload or structural cracks, occur when the applied load on a concrete structure exceeds its capacity to resist the stress. These types of cracks are typically more serious than surface cracks and can compromise the structural integrity of the concrete. Here are the primary causes of cracks in concrete due to overload:

Excessive Live Loads:

The most common cause of overload cracks is the application of excessive live loads on the concrete structure. Live loads include dynamic forces such as vehicles, heavy equipment, furniture, or people that are not part of the permanent structure. Overloading can lead to stress concentrations and structural failure.

Inadequate Design:

If the concrete structure was not designed to withstand the expected loads or if the design was not executed correctly, it may be more susceptible to overload-related cracking.

Material Weakness:

In some cases, the concrete mix used may not meet the required strength specifications, making the structure more vulnerable to cracking under load.

Foundation Settlement:

Settlement of the underlying soil or foundation can result in uneven distribution of loads on the concrete structure, leading to cracks. Differential settlement can cause one part of the structure to experience greater stress than others.

Improper Reinforcement:

Insufficient or improperly placed reinforcement, such as steel rebar, can weaken the concrete and make it more prone to cracking under load.

Impact Loads:

Sudden or impact loads, such as vehicle collisions, dropping heavy objects, or machinery accidents, can generate intense localized forces that can exceed the concrete's capacity and cause cracking.

Weak Points in the Structure:

Certain structural elements, such as beam-column connections, corners, or joints, may be more susceptible to stress concentrations and cracking if not designed and constructed properly.

Aging and Deterioration:

As concrete structures age and deteriorate due to factors like weathering, freeze-thaw cycles, or chemical exposure, their load-bearing capacity may diminish, increasing the risk of cracking under load.

Corrosion of Reinforcement:

Corrosion of steel reinforcement within the concrete can lead to expansion and increased internal stress, causing the concrete to crack and spall.

Earthquakes or Seismic Activity:

In regions prone to earthquakes or other seismic events, the sudden ground movement can impose significant loads on concrete structures, potentially leading to cracking and structural damage.

Preventing cracks in concrete due to overload involves proper design, construction, and maintenance practices:

Proper Design: Ensure that concrete structures are designed to withstand anticipated loads and that the design adheres to applicable building codes and standards. Quality Materials: Use high-quality concrete mixes and reinforcement materials that meet or exceed the specified standards. Regular Inspection and Maintenance: Periodically inspect the structure for signs of distress, such as cracks, and address any issues promptly to prevent further deterioration. Load Management: Implement load management practices, especially for structures that experience dynamic or heavy loads. Foundation Maintenance: Address foundation settlement issues promptly to maintain even load distribution.

Seismic Considerations: In seismic-prone regions, design structures to meet seismic codes and consider retrofitting existing structures to improve earthquake resistance.