Shrinkage is one of the main causes of cracking. As concrete hardens and dries, it shrinks due to the evaporation of excess mixing water. The wetter or dirtier the concrete mix, the greater the shrinkage. This phenomenon is known as plastic shrinkage and can be caused by a number of factors, but mainly by an excessive amount of water in the mix.
Adding more water can make concrete easier to work with, but once it dries, it can cause cracks. There are three types of everyday cracking: shrinkage cracking, settlement cracking, and thermal cracking. Shrinkage cracking occurs when concrete is placed in liquid form and then dries out. Settlement cracking is caused by an uneven base under the slab, which can cause it to sag or settle slightly and crack. Thermal cracking is caused by concrete expanding due to heat or swelling due to salts such as sulfates contained in the soil in direct contact with the concrete. To prevent these types of cracks from occurring, it is important to use the right ratio of water to cement when mixing concrete.
This will ensure that the concrete is liquid enough to be poured into the desired shape but not too wet that it will cause shrinkage cracks. It is also important to compact the base under the driveway properly and use a good quality concrete mix that has been formulated, placed, and finished correctly. Additionally, covering the concrete with an insulating plastic sheet or straw can help trap moisture and ensure an even curing process. If your concrete is a little older and has already developed cracks, a concrete repair professional can help you fix them. The ideal way to cure any concrete is to build barriers around the slab and flood the surface with water for at least seven days.
This will ensure a strong slab that will last for years. It may be tempting to add more water to make concrete easier to work with, but this is a mistake as it can greatly reduce its strength. Make sure your contractor knows at what force the concrete should be poured and consider using a sealing compound after it has fully cured to improve its appearance and reduce cracking. Good, strong, high-quality concrete requires an experienced team that knows how to use a slightly drier, stiffer mix. If any cracks appear soon after pouring, it's always a good idea to call a repair contractor to assess the problem.
