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Water reducers are special chemical products added to a concrete mixture before it is poured. They are from the same family of products as retarders . The first class of water reducers was the lignosulfonates which has been used since the 1930s.
Superplasticizers (SPs), also known as high range water reducers, are additives used for making high-strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more.
The performance of a concrete mix can be altered by use of admixtures. Admixtures can be used to reduce water requirements, entrain air into a mixture, to improve surface durability, or even superplasticise concrete to make it self-levelling, as self-consolidating concrete, [14] the use of admixtures requires precision in dosing and mix design ...
Raising the water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. Changes in gradation can also affect workability of the concrete, although a wide ...
A retarder is a chemical agent that slows down a chemical reaction.For example, retarders are used to slow the chemical reaction hardening of plastic materials such as wallboard, concrete, and adhesives.
Pages in category "Concrete admixtures" ... Water reducer This page was last edited on 29 November 2019, at 23:40 (UTC). Text is available under the Creative ...
Air entrainment in concrete is the intentional creation of tiny air bubbles in a batch by adding an air entraining agent during mixing. A form of surfactant (a surface-active substance that in the instance reduces the surface tension between water and solids) it allows bubbles of a desired size to form.
In order to reduce the energy consumed drying wallboard, less water is added, which makes the gypsum mixture very unworkable and difficult to mix, necessitating the use of plasticizers, water reducers, or dispersants. Some studies also show that too much lignosulfonate dispersant could result in a set-retarding effect.