Why RCC Slab Cracks After One Day Of Casting

 Why RCC Slab Cracks After One Day Of Casting

1. Environment Temperature –

 The weather in which you are casting your concrete is very vital for your concreting process. If you do not pay attention, then cracks are inevitable in your slab. You always try not to concreting in very hot weather. Try to concrete in the evening time so that the weather will cool down a bit. Due to the provision of concreting in more hot weather, the plastic shrinkage in the slab is developed, due to which the cracks are there, which we have to avoid.

2. Concrete Temperature –

 Now we will talk about the temperature of concrete, due to which there are chances of getting a lot of cracks. According to ASTM C 1064-4, the temperature of concrete should be in between 27.7 ° C to 35 ° C. If the temperature of concrete is more than 35 ° C, then we should use ice in concrete.

3. Water Cement Ratio – 

If the water-cement ratio is not maintained properly, its effect is seen in the form of cracks in the slab. Therefore, maintain the water-cement ratio mentioned in the mix design properly. Due to the high water-cement ratio, the concrete gets bleed, in which all the water of the concrete comes on the filter, which is a very vital reason for the cracks.

4. Compaction Frequency – 

During the casting of concrete we use a vibrator for compaction and for removing the voids. But excessive use of a vibrator is also not good for concrete. With this, the coarse aggregates settle down and fine aggregates start coming up due to which cracks are developed in the slabs. Therefore, keep this in mind while converting.

5. Presence of silt – 

The presence of silt in fine aggregate also results in hair cracks in concrete. If the silt is present in the sand, it will not be able to bond with cement due to which the concrete will not be set and there will be hair cracks in concrete. So we have to check properly the silt content in sand.

6. Reinforcement Temperature –

 Crack has also been seen occasionally due to the overheating of the steel bar used in construction works. Therefore, do not concrete casting in too hot weather.

7. Presence of Lubricant on the rebar – 

The application of grease or shuttering oil or any kind of Lubricant on the rebar can prove fatal for concrete. There will never be the bonding of concrete and bars due to which we can get cracks.

8. The difference in Slump Test Value – 

When we do casting on-site, we take a slump test by taking concrete from different lots. So the value of these different lot’s slump tests should not have much difference in the character, because of this also the cracks have been seen in the slab.

9. Types of Cement –

 You all know cement is of many types. Choosing the right cement in construction work can save you from getting cracks. You should choose cement keeping in mind the weather and work type. In the slab, if you use cement whose heat of hydration is very high, then the chances of cracks in the slab will become higher.

10. Overheating of shuttering material – 

Cracks can also be seen occasionally due to the heating of the shuttering material especially for Steel shuttering material. But the effect is very minor.

In this way, keeping in mind all these things, we can save the cracks from coming in the slabs.