Concrete mix for foundations | Useful information

The concrete mix for foundations depends on the type of foundation, nature of the subsoil, applied loads, durability issues, etc. There are many aspects to consider when deciding on a concrete mix for foundations.

The selection of the best concrete mix for foundations is made based on design standards and the experience of technical personnel.

How to make concrete for foundations

Mainly two types of concrete can be used for building foundations depending on the type of construction.

• Ready-made concrete
• Mix concrete by hand

Ready-mixed concrete can be used in larger construction works and in smaller projects, such as the construction of houses, smaller buildings or other smaller structures, the concrete can be mixed manually on site.

Factors to Consider When Choosing the Best Foundation Mix

Choosing the type of concrete or concrete mix for foundations must be done very carefully considering the following factors, as the concrete mix is ​​the main factor determining the Durability of concrete .

• Loads acting on the foundation

There is a relationship between structural resilience and concrete quality. Concrete is resistant to pressure and tension. Both tensile and compressive stresses can be observed in a section. Therefore, we have a superior concrete quality when greater loads are applied to the foundations.

Consequently, the concrete mix for foundation feet should be selected based on structural design requirements.

• Soil condition and exposure class

The concrete mix for the foundation pavement must be selected so that it can withstand the harsh environment or the foundation pavement is constructed in such an environment.

The exposure class must be determined when determining the concrete mix for foundations. Therefore Concrete quality The quantity based on the mixing proportions of cement, water and aggregates is determined according to the soil conditions.

• Groundwater

Groundwater may contain harmful chemicals such as chlorides, sulfates, etc., which affect the durability of concrete. A concrete mix with the highest content and resistance to these chemicals must be selected.

In this type of environment, ready-mixed concrete is more suitable for foundations than other types of concrete and must be selected with great care.

• Concrete durability

A durable concrete mix must be chosen. It must be able to maintain the condition of the concrete without deteriorating it in a way that affects the bearing capacity of the structural element.

• Concrete shrinkage

The concrete should shrink little. Although we cannot prevent the shrinkage of normal concrete, the lower the shrinkage, the better the performance of the concrete.

In addition, when finishing the concrete mix for the foundation, attention should be paid to shrinkage cracks.

• Concrete Workability and Why It Matters

Foundations do not have a high density of reinforcement. However, if there are two grids with closely spaced rebar, it may be necessary to pour workable concrete.

Additionally, workable concrete is easily compacted.

• Concrete Bagging

Concrete slump is an indicator of its workability. Therefore, the slump must be maintained adequate and the concrete mix proportions must be adequate.

Concrete mix for foundations

Let's discuss the mix ratio for foundation concrete. It depends on the factors discussed above.

In general, the minimum grade of concrete is 25 (C25). The mixing ratio of grade 25 concrete is 1:1.5:3 (cement:sand:coarse aggregate).

The article Concrete mix For more information on concrete mixes for foundations, see.

Depending on the building type and exposure class, concrete grades up to C40 can also be used for foundation construction.

What is the minimum quality of concrete for foundations?

This is an important question.

Because the quality of concrete depends on many factors.

Generally, the minimum grade of concrete we use as structural concrete is grade 25 concrete. Sometimes it is also considered grade 30 concrete.

Furthermore, it should be noted that the cement mixture for the foundation is the decisive factor that determines the basic properties of concrete.

How to Prevent Cracks in Foundation Concrete

Under very high loads, foundations are subject to tensile stresses. The bottom of the foundation is under tension.
If there are cracks in the concrete, they can widen and cause durability issues.

Additionally, there will generally be no top reinforcing mesh for foundations. If higher quality concrete with a thickness of, for example, 500 mm is used, there is a possibility of thermal cracking. Attention should be paid to this and, if necessary, top reinforcement can be provided to control cracks in the concrete.

Particular attention is paid to the hardening of concrete in addition. Curing improves durability and, if done correctly, can reduce cracking in concrete.

Therefore, special attention is required when selecting concrete mix for foundations.