The ready-mix concrete sector is going through a phase of transformation marked by the emergence of advanced concrete admixture technologies. For many years, multifunctional admixtures were the predominant choice because they provided greater plasticity and the ability to reduce the amount of cement needed in a mix, thanks to precise moisture control. However, the current landscape is marked by the arrival of several new types of admixtures, each with its own specificities and innovative capabilities.
This evolution is being driven by the growing demand for high-quality, durable, and high-performance concrete across a wide range of applications, from building and bridge structures to pavements and infrastructure works. The new admixtures are being developed to meet these specific demands, offering solutions that go beyond the capabilities of conventional products.
In this context, it is essential that ready-mix concrete companies stay up to date, in order to ensure they are using the best practices and technologies available to meet the needs of their operations. For this reason, this article explores some of the latest innovations in concrete admixtures, highlighting the new features that are driving the concrete industry into the future.
Getting to know the types of admixtures
To improve the quality of constructions and ensure the durability of structures, it is essential to know the different admixtures available. Below, learn about the main types used in the concrete industry, as well as their functions and benefits.
Calcium silicates
Advances in concrete admixtures are increasingly focused on increasing the strength and durability of structures. Calcium silicates are chemical admixtures widely used to improve the impermeability and wear resistance of concrete.
These admixtures penetrate the pores of the material and react chemically, forming crystals that fill the voids, making the concrete denser and more resistant to the penetration of aggressive agents, such as water and chemical products. This admixture not only extends the service life of structures, but also reduces the need for maintenance over time, resulting in cost savings for projects.
Set modifiers
Controlling the setting time of concrete is essential to ensure that the material is used effectively during construction. Admixtures such as set accelerators or retarders make it possible to adjust the hardening time according to the specific needs of the project.
Accelerators are used to speed up the hardening time, useful in adverse weather conditions or when the formwork needs to be released quickly. Retarders, on the other hand, are used to delay the setting time, providing more time for transporting and applying the concrete.
This precise control of setting time, in addition to improving work efficiency, also ensures the quality and durability of concrete structures, preventing problems such as cracks and fissures.
Air-entraining agents
The concrete admixtures known as air-entraining agents have the function of reducing the surface tension of water and introducing air into the concrete. This makes the material more cohesive and malleable, while also improving its mechanical properties and finish.
The effectiveness of these admixtures depends on the amount of crushing fines present in the concrete. The more fines there are, the less air is entrained. However, it is also important to note that an excess of air can reduce its mechanical strength.
Plasticizers
Plasticizers, also known as water reducers, are made up of molecules with negatively charged side ends. One of these ends bonds to the cement grains, which have a positive charge on their surface, while the other end, with a negative charge, remains exposed.
The electrostatic repulsion between the negative charges of the molecules and the positive charges of the cement grains causes them to move apart, improving the workability of the concrete.
These admixtures have as their main function to plasticize, that is, to increase the fluidity of the concrete without the need to add more water. This is done by maintaining the slump (a measure of concrete consistency) or even reducing the amount of water, which results in concrete with greater initial and final strength, without changing the setting time.
Superplasticizers
Superplasticizers are concrete admixtures that work in a similar way to plasticizers, increasing fluidity, but with the advantage that smaller amounts are needed to achieve the same effects. They achieve this by creating electrostatic repulsion between the cement grains, moving them apart from one another.
In addition, superplasticizers also separate the particles through steric repulsion. Currently, there are some that contain nanosilica, providing benefits to fresh concrete and increasing its durability once hardened.
Viscosity modifiers
Viscosity modifiers are admixtures whose main objective is to bind the concrete together, improving its cohesion and preventing the segregation of its constituent materials. They are formulated so as not to affect the plasticity of the concrete or the time needed for its setting, while also allowing the material to be pumped easily.
