Plasticizers
Plasticizers or water reducers, and superplasticizer or high range water reducers, are chemical admixtures that can be
added to concretemixtures
to improve workability. Unless
the mix is "starved" of water, the strength of concrete is inversely
proportional to the amount of water added or water-cement ratio. In order to
produce stronger concrete, less water is added, which makes the concrete
mixture less workable and difficult to mix, necessitating the use of
plasticizers, water reducers, superplasticizers or dispersants.
Adding 1-2% plasticizer per
unit weight of cement is usually sufficient. Adding an excessive amount of
plasticizer will result in excessive segregation of concrete and is not advisable. Depending on the particular
chemical used, use of too much plasticizer may result in a retarding effect.
Superplasticizers
superplasticizers, also known as high range
water reducers. These polymers are used as dispersants to avoid particle
aggregation, and to improve the flow characteristics of suspensions such as in
concrete applications. Their addition to concrete or mortar allows the
reduction of the water to cement ratio, not affecting the workability of the
mixture, and enables the production of self-consolidating concrete and high
performance concrete. This effect drastically improves the performance of the
hardening fresh paste.
