What concrete additives are used in construction?

Modern construction requires the use of specially designed solutions. In order for building structures to withstand heavy mechanical and physical loads, as well as those related to weather conditions, it is necessary to use special cement or concrete additives . Which of them are used most often?

What are concrete additives ?

According to PN-EN:206 (the current version is: PN-EN 206+A2:2021-08), a concrete additive is a fine-grained inorganic component used to improve or obtain special properties of concrete. It is most often added in an amount exceeding 5% of the weight of the cement.

The Polish Standard distinguishes two basic families of additives:

• type I - filling aggregate and pigments;
• type II - additives with pozzolanic properties (the ability to react with lime in an aqueous environment) and hydraulic properties.

It should be emphasized that the implementation of the solutions indicated in the PN acts is not obligatory. Many companies decide to do it for reasons of prestige. In some cases, a better solution will be the independent selection of cement or concrete additives, without following the guidelines of the standard.

What are concrete additives used for?

Products such as plasticizers, fly ash or polymer fibers allow you to modify the properties of both the concrete mix itself and the already hardened concrete. They improve its functional properties and allow the product to be adapted to the investor's requirements. Concrete for railway rail sleepers must have different properties than the raw material for floor screeds.

By using special cement additives , you can also save time and expense. For example , a quick-setting concrete additive allows you to shorten the time of construction work. In turn, plasticizers make it possible to reduce water consumption in the production process by as much as 30-35% while maintaining the same consistency and usable properties of the mixture. What concrete additives will you meet most often?

Plasticizers and superplasticizers

Additives from the family of plasticizers allow to reduce the internal tension of the mixture and the mixing water added to it. Thanks to this, the individual components are better combined with each other, and the concrete is easier to transport and pour faster.

The resulting mix is ​​more resistant to low temperatures than ordinary concrete. Greater cohesion translates into the mechanical strength of the raw material. Plasticizers also make the concrete mix look aesthetically pleasing, smooth and free of discoloration. This is important from the point of view of new trends in architecture, which are based on erecting structures of raw concrete.

An example of a plasticizer is e.g. CA40 FF and Rofluid M.

Fast-setting concrete additive

Another type of additive is concrete liquid , which accelerates the setting of the mixture. These types of preparations are used wherever it is important to complete the structure as soon as possible. They are used for sealing and when erecting objects that are in constant contact with water.

Appropriate selection of the proportions allows for obtaining the maximum strength of the material just a few hours after pouring it into the mold.

An additive to cement that delays setting

Construction companies that carry out works throughout Poland often use concrete additives that delay the setting of the mixture. Thanks to this, it becomes possible to transport it over long distances without worrying about the quality of the transported raw material.

Set retarders inhibit the access of water to cement particles, and thus slow down the crystallization process by up to 24 hours. It is also a popular solution when it is important to give the material a specific shape.

An example of a setting retardant additive is CP superplasticizer or BG97-40 superplasticizer .

Additives improving the aesthetics of concrete

Different types of additives differ in composition and application. In addition to substances that modify the performance properties of concrete, manufacturers sometimes also add compounds that only affect the aesthetics of the material. They include e.g. pigments and lime powder. They are referred to as neutral concrete additives .

Pigments cause changes in the color of the mixture. They are a frequent addition to architectural concrete. In turn, lime powder facilitates the transport and "pumping" of the material. Thanks to the binding of water, it is also more plastic and easier to shape.

A skilful selection of cement or concrete additives allows for more economical management of raw materials and achieving a better effect, both in terms of technical properties and appearance.

How to increase the strength of concrete in an aggressive environment?

Wherever the material is exposed to the forces of nature (rain, snow, stagnant water, hail), cement additives should be used to improve the strength of the concrete. One of such solutions are aerating mixtures. They cause that concrete does not absorb moisture, is resistant to rapid temperature changes and heavy loads.

The hydrophobic properties are also improved by sealing additives that clog the capillaries present in the concrete structure, thus preventing moisture from entering the material.

Substances that improve the aeration of the mixture are used in the production of paving slabs, pouring driveways or parking lots, as well as in the construction of stairs.

Where to buy chemicals for the construction industry?

When choosing a supplier of concrete additives , it is worth choosing a company that offers a wide range of products of the right quality. In this way, it is easy to adjust the composition of the mixture to the current needs, without having to wait for the delivery.

We recommend our offer to all construction companies. If you have any questions about the properties and use of specific products, we are at your disposal.

Well-chosen concrete properties guarantee the safety and usefulness of the building for many years. It's not worth saving on it!