What is the main concern when using superplasticizers in concrete?

The main concern when using superplasticizers in concrete is the risk of segregation. Superplasticizers are chemical additives that improve the workability of fresh concrete while maintaining or reducing the water-cement ratio. However, their use can lead to an increased risk of segregation, where the heavier aggregates settle at the bottom of the mix while the lighter components, primarily water and cement paste, rise to the top. This can result in uneven distribution of materials in the final product, negatively affecting its strength and durability.

Segregation can compromise the integrity of the concrete, leading to potential issues such as reduced load-bearing capacity and increased susceptibility to cracking and other failures. Proper mixing techniques and an understanding of the material properties are essential to minimize this risk when using superplasticizers.