Concrete and Pasticizer

Which Plasticizer Suits My Concrete Mix Design or Cement Type?

A question of growing importance, as the ambitious goals of the European and Austrian cement industries to produce climate-neutral cements by 2050 (Roadmap 2050) are expanding the range of cement types and additives used.

This commendable commitment, in addition to closing material cycles through the use of industrial by-products as cement additives and the development of new natural cement admixtures, leads to new challenges in concrete production. Besides the hardening behavior and the potential influence on durability parameters, the workability of fresh concrete becomes particularly important, as the interaction between cement and the appropriate plasticizer can lay the foundation for the later properties of the concrete.

Concrete Microscopy Provides Insight into the Microstructure!

Figure 1: Increased Capillary Porosity Around the Coarse Aggregate

A typical microstructure pattern of incompatible cement-plasticizer pairs is shown in Figure 1. Here, there is an increased occurrence of bond disturbances in the form of elevated capillary porosity around the coarse aggregate. The air pore system is not affected by this type of accumulation.

Although in this example the layers are only a few tens of micrometers thick, significant impacts on durability parameters can be expected, as diffusion processes are facilitated by the increased permeability. Additionally, mechanical losses in the form of reduced 28-day compressive strengths may occur. Therefore, it is recommended to test the combination of new cements with different plasticizers and also to examine the resulting microstructure. With this method, long-term durability assessments can also be carried out after just 28 days.

As the Saying Goes: There's a Lid for Every Pot, and the Right Plasticizer for Every Type of Cement!

The applications of concrete microscopy are very diverse and exciting! I am already looking forward to reporting on the next adventure in the infinite expanses...

of the concrete microstructure!