2. Actions of concrete admixtures

2.1 Improved processing conditions – Workability

Originally, the first additives were probably used to improve the mixing, placement and finishing of the plastic mixture. This last consideration is important for the architect, as it reduces or eliminates :

• penetrant testing ;

• SEGREGATION;

• the formation of pebble nests;

• unsightly surface defects that may result from the mixture's lack of plasticity.

Most of the admixtures used, whether air-entraining agents, set retarders or water reducers, improve workability. Although this improvement is considered a side effect, it is often the main reason for using admixtures....