Water reducers are special chemical products added to a
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
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. These inexpensive products were derived from wood and
paper industry
The pulp and paper industry comprises companies that use wood as raw material and produce pulp, paper, paperboard and other cellulose-based products.
Manufacturing process
The pulp is fed to a paper machine where it is formed as a paper web a ...
, but are now advantageously replaced by other synthetic
sulfonate
In organosulfur chemistry, a sulfonate is a salt or ester of a sulfonic acid. It contains the functional group , where R is an organic group. Sulfonates are the conjugate bases of sulfonic acids. Sulfonates are generally stable in water, non-o ...
and
polycarboxylate, also known as
superplasticizer
Superplasticizers (SPs), also known as high range water reducers, are additives used in making high strength concrete. Plasticizers are chemical compounds that enable the production of concrete with approximately 15% less water content. Superplast ...
s.
Water reducers offer several advantages in their use, listed below:
* reduces the water content by 5-10%
* decreases the concrete
porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measur ...
* increases the
concrete strength by up to 25% (as less water is required for the concrete mixture to remain workable)
* increases the workability (assuming the amount of free water remains constant)
* reduces the water
permeability (due to less water being used)
* reduces the
diffusivity
Diffusivity is a rate of diffusion, a measure of the rate at which particles or heat or fluids can spread.
It is measured differently for different mediums.
Diffusivity may refer to:
*Thermal diffusivity, diffusivity of heat
*Diffusivity of mass: ...
of aggressive agents in the concrete and so improves the durability of concrete
* gives a better finish to surfaces (due to all of the above)
See also
*
Plasticizer
A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture.
Plasticiz ...
*
Superplasticizer
Superplasticizers (SPs), also known as high range water reducers, are additives used in making high strength concrete. Plasticizers are chemical compounds that enable the production of concrete with approximately 15% less water content. Superplast ...
*
Cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
*
Admixture
Building materials
Cement
Concrete
Concrete admixtures
{{Chemistry-stub