Concrete, which is known for its strength and durability, is the most commonly used building material. Concrete is made from a mixture of Portland cement, sand and water to construct architectural structures, foundations, walls, pavements, bridges etc. But d0 you ever wonder why does concrete show damage in the form of cracks, which can range from light surface fractures to holes that are large enough to make a structure unusable?.
The various factors that normally cause concrete to crack are –
Shrinkage : It occurs as the material dries. When concrete cures, the water mixed with the cement and sand begins to evaporate leaving empty voids in concrete structures, making them weak and they start shrink. The tension on weak materials and resistance restrained by the surrounding materials leads to cracks.
Temperature Changes : Shift or variation in temperature causes abnormal expansion and shrinkage between different layers of concrete which cause cracks in large structure and applications.
Lack of Support : Inadequate structural support sometimes causes severe cracks in concrete. Poor structural support is mainly due to poor installation, including improper use of rebar or insufficient form work. In addition, soil erosion due to wind and rain, which leads the soil beneath the concrete slab to shift in position can also cause poor structural support..
Rusting : Almost all the concrete structures contain metal reinforcement which helps in increasing the material’s strength. When these metal reinforcements start to rust, they cause the concrete to expand and as a result hairline cracks and small surface cracks appear.
Spalling : When too much water is added to the concrete mixture, or when the surface layer dries faster than interior layers, hundreds of tiny crack, appear on the surface of the concrete making it rough and flaky.
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