Concrete Cracking: Know its Types & Appearance at Various Age

Concrete, revered for its durability and versatility, forms the backbone of countless structures worldwide. Yet, even this stalwart material is not immune to the passage of time and the myriad forces that act upon it. Throughout its lifespan, concrete faces a constant battle against cracking, a phenomenon influenced by a plethora of factors ranging from environmental conditions to structural loads. In this article, we embark on a journey through the ages of concrete, exploring the diverse types of concrete cracking that manifest at different stages of its existence.

The occurrence of cracks is often a subject that raises numerous questions. Cracks may appear in structures, either at the initial stage or with time, and some types of cracking are unavoidable in the house. Cracks may be big or small, structural or non-structural, or in various shapes, widths, and patterns.

Types of Concrete Cracking and Their Appearance at Various Ages

Concrete, though robust, is susceptible to cracking due to various factors ranging from external loads to internal chemical changes. These cracks can manifest at different stages of the concrete’s life, from the fresh, plastic state to hardened structures. Let’s delve into the types of crack appearance across different ages of concrete.

As cracking in concrete structures is inherent, what matters is the type of structure and the nature of cracking.

 Plastic Shrinkage Cracks

• Appearance: These cracks typically occur during the early stages of concrete curing, when water evaporates rapidly from the surface.
• Plastic shrinkage cracks appear as shallow, random, interconnected lines on the surface of the concrete.
• Often observed within hours to a day after placement, especially in hot and dry weather conditions.

 Plastic Settlement Cracks

• Appearance: Formed due to the settlement of heavier aggregate particles in fresh concrete.
• Plastic settlement cracks are often V-shaped or have a triangular pattern.
• Typically seen within the first few hours after pouring concrete, and are more common on large horizontal surfaces like slabs.

Cracks Due to Corrosion

• Appearance: Occurs due to the expansion of reinforcement steel as it corrodes.
• Cracks may appear as localised, irregular patterns near reinforcement bars.
• Often observed in older concrete structures, especially those exposed to chloride ions or carbonation.

Cracks Due to Loads

• Appearance: Results from excessive external loads exceeding the concrete’s capacity to withstand.
• Cracks can vary in size and shape, ranging from hairline cracks to wider fissures.
• Typically seen in areas subjected to heavy traffic or structural overloading.

 Cracks Due to Dead Weights

• Appearance: Results from the settlement of heavy objects or structures on concrete surfaces.
• Concrete cracking may appear as straight lines or as patterns resembling the shape of the load.
• Commonly observed in structures with inadequate support or improper distribution of loads.

Cracks Due to Chemical Changes in Hardened Concrete

• Appearance: After one or even after many years, depending on a chemical attack from outside.
• Arise from chemical reactions within the concrete mass leading to expansion or contraction.
• Cracks may exhibit a variety of patterns, depending on the specific chemical reaction.
• Common examples include alkali-silica reaction (ASR) cracks or sulphate attack-induced concrete cracking.

Let’s understand concrete cracking appearances at various ages with the help of a table.

Key Takeaway: Understanding the types of concrete cracking and their appearances at various ages of concrete structures is crucial for effective inspection, maintenance, and repair. Early detection and appropriate remedial measures can help mitigate the detrimental effects of cracking, ensuring the longevity and structural integrity of concrete elements.

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