Superplasticizers, retarders, and accelerators are examples of concrete ___.

The correct choice is "admixtures" because superplasticizers, retarders, and accelerators are substances added to concrete to modify its properties. Admixtures are specifically designed to enhance the performance of concrete in various ways.

Superplasticizers improve workability by allowing for the construction of high-strength concrete with less water. Retarders slow down the hydration process, which is beneficial for working with concrete in hot conditions or when delays in pouring are unavoidable. Accelerators, on the other hand, speed up the curing process to achieve faster setting times, particularly useful in colder weather or when quick construction turnaround is needed.

This terminology is important in the field of concrete technology, as understanding the role of different admixtures helps in selecting the right materials for specific construction requirements.