Usually, concrete takes around one to two days to dry correctly, depending on the environment. You can walk or perform other tasks on a concrete structure approximately seven days after it is laid.
However, the concrete is at around 70% of its total strength at this stage, so it is best to avoid driving or using heavy machinery on it.
During the curing phase, the concrete starts to harden, but this does not have any effect on its structural strength.
When cement, water, and aggregates are mixed to form concrete, the cement particles start bonding with water particles. Read on further to learn more about how long concrete takes to set.
How Long Does It Take For Concrete To Cure Completely?
The curing period of concrete takes around a month, but it becomes ready to use within a week. The settling and curing time of the concrete mixture varies for each project due to differences in climatic conditions, type of mix, application, and finishing technique.
If you want to know more about how long concrete requires to set, then keep the following time frames in mind.
- 24 to 48 hours – This is the time for the initial setting. Later, forms can be removed, and people can be allowed to walk on the surface.
- 7 days – duration for partial curing. After which, vehicles and equipment can be allowed to run on the surface.
- 28 days – At this stage, the concrete is completely cured and ready for use.
Factors That Affect Setting Time Of Concrete
The most crucial factor that affects the setting of concrete is the presence of moisture. Concrete structures require the right amount of water to attain their maximum strength.
The presence of excess water in the concrete causes it to harden too fast and reduces structural integrity and stability.
Avoid using excess water in a concrete mixture as it ruins the consistency and strength of the mix.
How To Make Fast-Setting Concrete
Understanding the steps of mixing concrete is crucial to prepare a concrete mix for different purposes. For example, some applications require fast curing of concrete structures, and builders use accelerants to set the concrete quickly. However, the use of accelerants affects the strength of concrete after its setting.
Use Of Concrete Blankets For Speeding Up The Curing Process
Concrete blankets help in maintaining hydration in the initial stages of the curing process.
They also protect the concrete structures from extremely cold temperatures, thereby eliminating the risk of thawing and maintaining the structure’s structural strength. As a result, concrete blankets are suitable for all types of concrete jobs.
In addition, the portability of the blankets makes them ideal for carrying around different job sites.
What Is Curing, And How Does It Affect The Concrete?
The curing of concrete structures has two main applications.
- It helps in retaining moisture in the concrete slab so that it continues to gain strength.
- The curing process delays shrinkage, and concrete gains sufficient strength and resistance against shrinkage cracking.
Proper curing of concrete is necessary to improve its durability, wear resistance, water tightness, and strength.
The durability of a concrete slab is primarily affected by the growth of crystals within the concrete matrix. Crystals grow due to the reaction between water and Portland cement, commonly known as hydration.
Lack of sufficient water prevents crystals from growing, and concrete structures do not have adequate strength. However, if there is adequate water, concrete crystals grow into tiny finger-like structures that wrap around the gravel and sand mixture.
Temperature also plays an essential role for the concrete to set. As freshly laid concrete starts to cool, the hydration reaction in the molecules reduces.
Hence, the temperature plays an important factor that affects the curing and strengthening of concrete structures.
When Is The Right Time For Curing Concrete?
In the initial stages of curing concrete, the two most important factors are water content and temperature. The most common mistake in the curing process is keeping the exposed concrete surface moist during the hydration process.
All types of concrete usually have sufficient water content to facilitate complete hydration.
But when the surface completely dries out, the hydration process stops, and the concrete particles start shrinking.
The curing process typically includes three phases, and the length of these phases depends on the type of concrete mix and environmental conditions.
- When the fresh concrete mix is first laid into a slab, water rises as the mixture settles down. During this period, the water evaporates from the surface when it is rising out of the concrete. At this stage, some initial curing is necessary to prevent shrinkage and cracks. Therefore, knowledge of the evaporation rate is vital during this point of the process.
- The intermediate stage is the phase between the initial and final set. It is necessary when the finishing and curing are complete before the final set.
- In the final setting, the curing is complete.
Setting and curing concrete is an essential process. The type, quantity and application of the concrete primarily affect its curing process.
Therefore, one must always take advice from a reputed supplier or builder to ensure the selected concrete mix is suitable for a specific application.
- Is it necessary to wet concrete while curing?
It is essential to keep the concrete mix hydrated during the hardening process. Always maintain the proper ratio when preparing the concrete mix to ensure that it hardens and cures properly. Water should be applied for the first seven days of the hardening process.
- How long does it take to cure a 6-inch thick concrete layer?
Freshly laid concrete takes around 30 days to attain its full strength. However, if the mixture is poured and floated professionally, the curing process will be perfect.
- After how long can anyone walk on concrete?
Avoid walking on freshly laid concrete for the first 24 hours. Then, leave the surface for at least seven days before using heavy machinery or vehicles on it.
- How long does concrete take to set in a post hole?
Concrete inside a post hole takes at least four hours to set. Therefore, avoid applying any kind of weight or pressure on the post during this period.
Ideally, the post must be left for 24 hours before applying any external force.