In due course of time you will find a number of slab problems and as a houseowner you need to find solution for such problems. In this write-up we shall discuss about few common problems and identify their solutions.
- Plastic shrinkage crack
It is very common to find such crack marks on the surface of concrete slabs and you can observe it only when you check the surface very closely. As such, this type of plastic shrinkage crack is cosmetic in nature and remains limited within the surface only. The performance of the slab is least affected due to this problem. What you will see is very fine line of thin cracks. It is generally caused by the shrinking and drying of the surface while it is still in plastic stage.
To prevent such occurrence, you must use less water in mix and dry by using wind and sun. Try to cure with water mist. Some people suggest polishing in order to solve the problem however it will not be completely removed. Since, such problem does not affect the service of the concrete, so you need not bother much about it.
Scaling is a thin layer of surface that gets pasted on the slab which breaks up in order to reveal the problem. It is generally caused by shortage of entrained air on the surface layer or salt appearing on the surface of the slab before it is dried up and obtains necessary strength.
To prevent the occurrence of scaling it is necessary to ensure that there is quite an effective air void system. In order to ensure that it is necessary that air that you are delivering on the concrete must be about 5 to 8 per cent. In order to ensure this, what you need to do is to check the concrete’s weight against the specification. Also, you can do proper air content testing too.
You must remember that if you do over finishing on the surface of concrete then you will drive out the air from its layer. This way, it will be more susceptible to damage due to freeze thaw. You also need to ensure that deicing salts do not come on the surface till it dries up at least for a month. In such freeze-thaw environment, compressive strength should be 3500 to 4000 psi.
You can fix by sealing the surface so that water is not allowed to enter.