Grout: types? How to prepare? Composition and Yield

September 17, 2021 by No Comments

Have you heard of grout? The concrete mass is an important part of the masonry works and guarantees greater resistance to the building. In any case, attention is needed when preparing and applying it, in order to obtain the best result.

Imagine building a house out of ceramic bricks. It may seem that the concrete used works only to “glue” the layers of pieces, but it does much more than that. In fact, the mass of cement and aggregates also fills each brick, so that it becomes completely “solid”. That is, there will be no empty space in the pieces.

To begin with, this care makes the property more resistant. After all, it is much easier to break a ceramic piece with “holes”, than one filled with concrete.

At the same time, the grout provides an improvement in the building’s acoustic capacity. This is because the sounds will find a new barrier to enter or leave the space. There is also an improvement in the durability of the building, as well as its thermal capacity.

What is the groute for?

In this way, the main objective of the grout is to fill the empty spaces of the blocks and channels of a construction. Thus, it can solidify the building’s armor, and increase its bearing capacity. That is, to support all the remaining weight of the structure.

Another common function of the mass is the fixing of equipment bases and small machines in the work. As well as minor repairs, made on the concrete floors. Thanks to its greater fluidity, the composition is still widely used in spaces that are difficult to access in a building. Like cavities with obstacles (like pipes and reinforcement).

The important thing is to fill, whenever possible, all the gaps available in the work. This will ensure the property’s strength and durability for years to come.

What are the characteristics of grout?

As mentioned, the grout is a concrete with greater fluidity than that commonly used in the works. Not only this fluidity, however, is responsible for defining the product. The dough must have other characteristics. Otherwise, it will be taken as another type of concrete-like pumpable, which is also fluid.

Both the fluidity of the concrete is considered because it allows simple spreading of the mass through the gap, without the need for densification. This feature still guarantees volumetric stability, with perfect adherence and complete filling of the voids.

It does not mean, however, that the grout must be fluid like water, spreading out of control. In fact, its spreading is controlled, so that only the necessary is applied to the surface. In addition, the dough must reach high initial and final resistances.

Grout composition

When using grout in a work, the engineer or architect is able to enhance the strength of the structure between 30% and 40%. For this result, however, it is necessary to produce the concrete with the appropriate proportions of each component.

In the so-called fine grout, the material is produced only with cement and sand. The thick version of the product adds a mineral to the mix, making the product “heavier” and thicker.

In addition to these components, the mixture includes water and lime. Another additive may also appear, such as super plasticizers, anti-wash additives and water-retaining expanders. Among the minerals suggested for the dough, it is common to use common gravel, silica fume, quartz, granite, pozzolans and limestone.

As mentioned, the proportion of each product in the mixture makes a complete difference and must be thought out according to the location and purpose of application. To obtain the best concrete, it is important that the work has an expert on the subject, be it an engineer or an architect. Evaluating each aspect of the building, the professional can make the necessary calculations for the most advantageous result to the property.

The types of grout

There are two types of grout available on the market, classified according to their composition and indication of use.

In the first, called cementitious, or mineral-based, the dough is produced through the use of large gravel. The product is suitable for repair works, submerged applications and works at high temperatures. As for buildings and industries, and for injections (with aggregates smaller than 75 microns).

Second, there is the organic-based grout, or resin. The material is applied in situations that require high adherence, such as grouting tunnels. This type of concrete is also ideal to meet the need for mechanical, chemical and oil resistance of the property. Especially since, it has excellent vibration absorption capacity.

With the organic material, prestressing cables and geotechnical applications (landfills, foundations, retainers and others) are also usually grouted.

How to prepare grout in the work?

For the application of grout to be properly carried out, it is necessary to work on four stages of preparing the space and the dough.

It is essential that each phase is carried out carefully, in order to reach its maximum potential. Otherwise, the error in one action can have effects on all others, making the result of the construction less than desired. Follow the steps and tips for carrying out each one below.

1. Preparation of the work

The main care indicated in the preparation of the work is the cleaning of the place where the grout is applied. This is because dirt, including oils and greases, can impair the adherence of the grease to the surface. If it does not adhere well to the space, the cement does not reach the resistance and the other objectives already mentioned in the text. Therefore, it would be useless to apply it.

After cleaning the area, it is interesting to define the spaces that will receive the grout. Especially if this space is the ground. After all, the dough is highly fluid, and could spread to unwanted locations for the work.

Then, just saturate the prepared surface with water, always avoiding the puddling of the liquid. This makes the space moist and more receptive to the application of the concrete mass.

2. Mixing the dough

There are several basic indications for the preparation of grout, which we will quote below. However, it should be noted that the instructions and quantity of inputs needed may vary according to the work. That is why it is so important to place the command of construction under the baton of a competent and experienced engineer or architect. Only the specialist can verify the specifics of the construction and indicate necessary changes.

In any case, the indication of using a low lime content is common. This care decreases the chance of mass retraction failures, ensuring greater product adherence. In order to guarantee the fluidity of the material, it is interesting to treat the water/cement ratio as 0.9. Meanwhile, the concrete’s resistance to pressure must be at least 14MPa.

All this mixing, including the necessary aggregates, can be carried out manually at the construction site. For large quantities, however, it is more interesting to invest in a forced action mixer or similar equipment. More than streamlining the process, this method of preparation will guarantee the homogeneity of the concrete. In other words, it will allow the same mass to be used in large areas, reducing the risk of significant differences in the structure.

When this type of care is not performed, one wall may become more resistant than the other, for example. No major apparent problems, is there? However, the unbalance of the structures can put excessive pressure on a space, causing its premature wear.

Mixing is usually quick, taking just 5 minutes. Depending on the type of concrete, it is recommended to add up to 30% of gravel or other minerals to the mass, but no more than that. Thus, the fluidity of the product will be maintained. Regardless of the type of aggregate, it must be added clean and dry to the mixture.

3. Application of grout

As with the previous steps, the application of grout deserves intense dedication. The care aims to ensure that the putty is applied in the correct quantity and in the correct places, spreading and completely filling all the available space.

Due to the fluidity of the mixture, it is recommended to continuously pour it into the area to be filled. Something similar to the action of an individual who pours water from one bucket into another bucket. This prevents the creation of bubbles and facilitates the compacting of the material.

In addition, the process becomes faster and simpler, as applying the concrete with a trowel can be a problem. In that case, the chances of the material dripping and being wasted would be great! The use of a concrete injection is also possible.

It is also necessary to avoid the need to perform the mass after its application. That is, she must settle on her own, instead of being forced to do so. The ideal is to smooth the surface just enough to make it flat and regular for the continuity of the work.

4. Curing of concrete

Finally, there is the stage of curing the grout, drying it. A necessary precaution in this phase is to prevent the product from drying out all at once, too fast. This is because, concrete is a material subject to breaks and cracks, which happen mainly in situations of fast curing.

Therefore, chemical curing is usually used, in which a specific material is applied to the surface. It prevents the concrete from suddenly losing moisture.

It is also possible to do a wet cure, in which small portions of water are applied over the area. However, this process takes a little longer, lasting about three days. It is important, in both options, to avoid direct sunlight on the concrete.

What is the grout yield?

Grout yield varies according to the product’s brand of manufacture. Yes, differently from what you have thought so far, grout can be purchased ready-made, in addition to being prepared at the construction site. The options usually have similar prices and are chosen based on the type of work and the preference of the architect and/or responsible engineer. In any case, ready-mixed concrete generally requires less labor and construction time.

It is possible, in any case, to establish an average yield of the products, regardless of the brand or own production. According to experts, when a single layer is used (with a thickness of up to 900 square cm), the grout has a yield of 5 kg per square meter. In a double layer, with a thickness above 900 square cm, it is necessary to have 8 kg of material per square meter of the work.

What are the advantages of grout?

With all that we have mentioned so far, you have already noticed some advantages of using grout. Like creating greater resistance to construction, ensuring its durability. In addition to these, however, there are a number of other interesting benefits to Civil Engineering works across the country.

So, let’s start with the speed of the process. By using the grout, the person responsible for the work is able to carry it out in a shorter period. After all, the product is easy to handle, and avoids the need to work with compact bricks. A compact brick is one that has almost no holes, and is heavier. This weight reduces the pace of construction execution.

Another advantage of the option is its ease of filling even small gaps. Fluid, the product reaches spaces more quickly, even avoiding air pockets.

This type of material guarantees even greater protection against corrosion of the properties. The feature exists thanks to its low permeability, that is, its low water absorption. Here, the steel structures of the property are preserved, which could rust if there was a risk of liquid accumulation.

Finally, it is necessary to mention the excellent finish provided by the product, since it rests easily on the surface on which it is applied. It is only necessary that the person responsible for the work quickly level the area after the application of the material.

Gross price – How much does it cost?

Grout costs vary, according to the region of the country and the brand of the product. It also varies if the concrete used is produced at the construction site, since it is necessary to consider all the materials needed for production.

We can still quote an average price of the product on the market. Of course, based on the ready-made pasta. Generally, a 20 kg container of concrete costs just over R $ 35.

Whenever possible, it is interesting to obtain, at once, all the material necessary for the work. Thus, the consumer tends to get discounts at the building materials store.

Even better if the purchase is made in cash. Therefore, always carefully evaluate the construction planning and, together with the engineer/architect responsible, establish everything necessary. Your pocket will thank you, both in the purchase of the grout, and of other products necessary for the building.