One of the most common questions received is about cracks that are developing in newly poured concrete. The homeowner will question why it is cracking and did they receive a shoddy job.
Sources Of Cracking In Concrete
Excess water in the mix
Concrete does not require much water to achieve maximum strength. But a wide majority of concrete used in residential work has too much water added to the concrete on the job site. This water is added to make the concrete easier to install. This excess water also greatly reduces the strength of the concrete.
Shrinkage is a main cause of cracking. As concrete hardens and dries it shrinks. This is due to the evaporation of excess mixing water. The wetter or soupier the concrete mix, the greater the shrinkage will be. Concrete slabs can shrink as much as 1/2 inch per 100 feet. This shrinkage causes forces in the concrete which literally pull the slab apart. Cracks are the end result of these forces.
Lack of control joints.
Control joints help concrete crack where you want it to. The joints should be of the depth of the slab and no more than 2-3 times (in feet) of the thickness of the concrete (in inches). So 4″concrete should have joints 8-12′ apart.
Use of inferior materials:
One of the key sources is that the use of lower quality materials that embrace each concrete and steel in reinforced concrete structures.
Mistakes at design stage in office:
If there area unit errors at style stage then it’s obvious that issues can occur at site. concrete cracking is one in all them.
Shrinkage will cause cracking if not controlled throughout combine style and hardening stage. Shrinkage will become essential in high strength concrete attributable to low water/cement ratio and conjointly attributable to use of Mineral Admixtures.
Overloading of structure:
Overloading of structure particularly at younger age may be a common supply of cracking. This will happen if formwork is removed before time or additional construction load is present.
Use of engorged Reinforcement in Lean Concrete:
If you employ serious reinforcement in average quality concrete then stress distribution between steel and concrete will become non-linear inflicting cracking..
Another major reason for concrete cracking. If hardening isn’t done fitly for given time span then one ought to expect cracking.
Early Formwork Removal:
If formwork is removed before concrete has achieved strength, there’ll be cracking.
Quality and sort Of Aggregate:
The quality of combination employed in concrete determines the general strength of concrete. If the combination is of poor quality it’ll not create a correct bond with cement.
Mistakes at site : Proper and trained labour and acquisition area unit necessary for any site work. Lack of it throughout concreting will cause cracking.
Throughout erection :
This is also a reason for cracking in concrete.