Achieving quality control and assurance at the desired level is a must for all construction work. The quality of the work is not controversial. It must be achieved by all means. It is common to see that the structure develops cracks due to construction defects.
Poor quality construction work and lack of attention from contractors result in lower quality work and incur additional costs for the contractor. Furthermore, it is a burden on the engineer and the owner. This remediation work requires additional time, resulting in project delays.
Commonly observed design defects that lead to cracking are as follows.
- Honeycomb formation
- Mix design
- Premature removal of the formwork under the panels
- Premature stripping of thick concrete formwork
- Start slab work in advance
Honeycomb formation
This is due to a lack of care in the works. The main causes of honeycombing are reinforcement overload, mortar leaks, poor compaction, etc. The outer honeycombs are visible to the naked eye due to the internally formed honeycombs, which are not visible from the outside. Inner honeycombs are not common and outer honeycombs are often visible. Inner honeycombs are more dangerous because they are not visible and therefore not repairable like outer honeycombs. The existence of these honeycomb leaks can cause cracks in the structure and even lead to failure of the structure if the damage is severe.
Mix design
Due to the incompatible properties of concrete, cracks form in structures. Cracking may occur due to creep and shrinkage effects, shrinkage during drying, etc. (see above). The composition of the mixture must correspond to environmental conditions, design conditions, pouring times, etc.
Premature removal of the formwork (ceiling soffit)
Formwork must be removed as recommended in the specification/guidelines or as recommended by the structural engineer. Engineer's advice should be sought to remove the floor formwork after concreting as it depends on increasing the strength of the concrete. Concrete test cubes poured during concreting can be tested to determine whether the concrete has reached the strength required for removal from the formwork. Removing it prematurely when the concrete has not yet reached its strength can cause deformations and cracks in the concrete.
Premature removal of formwork (thick concrete)
Formwork removal time depends on model test information. The moment of removing the formwork is determined depending on temperature fluctuations. Early removal of the formwork changes the temperature difference and gradient and begins to adapt to environmental conditions. This leads to cracks in the concrete inside and out.
Start working on the record early
The formwork can be removed when the concrete reaches a certain strength. If work on the upper floor begins immediately after removing the formwork, the beams and slabs may crack. For example, the contractor can continue with the pour columns as this will not directly impact the ground. However, if he builds brick walls, the load will increase significantly. Bricks must be stored in the ground before construction, and construction work puts additional pressure on the ground. Therefore, if there is not sufficient information to prove that the concrete can withstand these loads, the works must be carried out in accordance with the general standards and relevant technical specifications.
