Workability is one of the most important characteristics of concrete especially under the following circumstances:
- If the concrete is to be placed around closely placed reinforcement or in difficulty accessible sections.
- Where special means of placement are required such as tremie, chute or pumping methods.
- If the concrete is harsh because of aggregate characteristics or grading
The materials used as workability agents are:
- Finely divided material
- Water reducing agents
- Air entraining agents
- Common materials added as workability agents are bentonite clay, diatomaceous earth, fly ash, finely divided silica, hydrated lime and talc
- When they are added and if the quantity of water is not reduced they greatly increase the workability.