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In reinforced concrete structures, cracking is a common phenomenon. As mentioned earlier, there are structural and superficial cracks. The one we should worry about is the structural crack. Hence, if encounter such crack, it requires our concern which translate into the requirement of an inspection and investigation.
Why do concrete cracks? There are four main reasons:
1. Excess water in the mix
- The associated problem related to this is wet shrinkage.As concrete hardens and dries, it shrinks.
2. Rapid Drying of the concrete
- This occur during the curing process. Curing is an important process; serving two pusposes: 1. It retains moisture in the slab so that the concrete continues to gain strength and 2. It delays drying shrinkage until the concrete is strong enough to resist shrinkage cracking. Improper curing will result is crack to appear.
3. Improper strength concrete poured on the job
- Concrete can be engineered to a specific strength depending on the purpose it was intended for. Make sure that the concrete you require is the same as what is ordered (from the factory) or designed (in-situ casting). Excessive load exerted on the structures will eventually leads to cracking.
4. Lack of control joints.
- Control joints are needed when you are expecting expansion/shrinkage of concrete due to temperature changes and drying shrinkage. Spaced the joint correctly.
Dr. Ibrisam Akbar