HOW TO AVOID CRACKS WHEN POURING CONCRETE

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How to Avoid cracks when pouring concrete It is one of the most popular topics in recent times. Dufago Concrete will offer the following solutions, which you can refer to and apply to your works and projects:

By following a few simple steps before and after placing fresh concrete, you will achieve a beautiful concrete texture that requires very little maintenance, minimizing cracks in the concrete.
Concrete is basically composed of cement, stone, sand and water. When fresh concrete is at the plastic stage, it is fresh concrete in a flexible form. As the concrete becomes harden, the cement mortar begins to shrink, and the small strength values obtained when the concrete is young cannot withstand the stresses created by this shrinkage.

If fresh concrete is poured on a windy day, the surface may begin to set before setting on the bottom, which will cause the concrete to shrink unevenly (plastic shrinkage cracks). Also, if the ground beneath the concrete is uneven, there will be an uneven tensile force during the concrete shrinkage, which also causes stresses that adversely affect the new concrete. So how do you get concrete with no cracks?

Before pouring concrete

What to do before pouring concrete to avoid cracks when pouring concrete. First make sure the foundation layer (soil underneath the concrete) is compacted and completely leveled. The best thing to do is to use a garden tiller, till the soil to a depth of 15.24 cm, then hire a hand operated compactor and compact the soil thoroughly.

This will help ensure no weak background spots appear. A buffer sand can be added if desired, which will help achieve a perfectly flat surface and provide constant friction to the shrinking concrete. 10.16cm of washed sand is enough to spread the buffer layer. If wire mesh is used as reinforcement, flat nets should be used, not coiled nets. Wire mesh is extremely difficult to hold in the top half of the concrete, where the wire mesh needs to be positioned to work.

Reinforcing bars connected by steel wires can also be used, but the spacing and dimension requirements vary depending on the load and soil conditions, as it is difficult to recommend a standard. standards for that matter. If rebar is used, it is essential to keep the rebar in the top half of the concrete; You can use stones, broken bricks or you can purchase plastic spacers on which the steel will be placed to keep them in place when the concrete is poured.

Or you can also ask the fresh concrete company to supply the fibers for the pouring mix. These fibers are usually nylon or polypropylene fibers, which help to minimize cracks in concrete at the micro level rather than at the macro level (where cracks are visible to the naked eye). Reinforcing also helps control cracks, but if a crack occurs, the steel, when properly placed into the concrete, will hold the concrete together, whereas the fibers will not.

When the concrete is fresh, if there is no vapor isolation layer, wet the base layer without stirring the water so that the water in the fresh concrete will not be absorbed by the dry base layer, which causes uneven drying and bad cracks caused by plastic shrinkage.

As soon as the fresh concrete is finished pouring

Immediately after pouring concrete, the following steps should be taken to avoid cracks when pouring concrete. It is necessary to protect the concrete from strong winds and from being exposed to direct sunlight as the concrete will dry evenly from top to bottom. In order to prevent significant cracking, expansion joints are important to prevent cracking. By creating expansion joints that are at least 1/4th the thickness of the concrete and spaced by about 25 to 30 times the concrete thickness (it's usually easiest to use a trowel or construction tool when the concrete is ready). concrete is still fresh), will almost guarantee no cracks appear in the concrete.

If the floor is 10.16cm thick, the expansion joints must be at least 2.54cm deep and spaced every 254 - 304.8cm/slot. If it is not possible to use construction tools to place the joints in, a contractor can be hired to cut the concrete to create expansion joints with a minimum depth of 1/4 of the thickness of the floor. This bonding method will allow the concrete to crack at its weakest point, which is why having the expansion joints deep enough is so important. Changes in foundation heights can cause greater stress in the concrete where the joint has not reached sufficient depth, and the concrete will crack outside the joint.

As soon as the expansion joints are in place, and the concrete has cured for about two weeks, seal the joints to prevent water from entering the foundation and causing scaling, or penetration. enter the expansion joints and cause freezing there, causing the water to expand and break the concrete around the joints.

The most common method today is to conduct regular watering after a few days of pouring concrete or using the method of using absorbent sacks on the concrete surface. With a large concrete structure, the expansion joint is an important factor to avoid cracking. The expansion joint is at least 1/4 of the thickness of the concrete, the distance between the joints is at least 25 times the thickness of the concrete. Doing so will ensure that no concrete cracks are visible, ensuring aesthetics.

If the floor is >10 cm thick, proceed to create expansion joints. These slots need to be at least 2 cm deep and spaced every 250 – 3000 cm/slot. Use the expansion joint tool with a depth of at least ¼ of the floor's thickness. Applying this method will help the concrete crack at the weakest point, the expansion joints have a sufficient depth. In case the joints are in place and the concrete cures for 2 weeks, do not forget to seal the joints. The purpose of this action is to prevent water from entering the foundation layer. Thereby causing the phenomenon of expansion, penetrating inside the joint, causing freezing, creating cracks.

How to avoid cracks when pouring concrete has been shared in the article above, surely this article will bring useful information to customers who need to pour concrete in the near future.

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