Concrete admixtures (additives) enhance the performance of concrete and are suitable for architectural applications with special requirements. Concrete additives are used to achieve the desired processability at low water to cement ratios and to increase the set time of long distance transport of concrete.
The properties of hardened concrete, mortar and grout should be changed to: delay or reduce heat assessment during early hardening. Speed up the development of early power. Increase the strength (compression, stretching or bending). Increase durability or resist severe exposure conditions.
Reduce the permeability of concrete. Controls the swelling caused by the reaction of the base with certain aggregate components. Increase the bond between concrete and steel. Increase the bond between existing and new concrete. Improve impact resistance and wear resistance. Suppresses corrosion of embedded metals. Production of colored concrete or mortar.
Why use a water reducing agent?
a) Produce concrete with better processability without requiring more water, so no loss of strength is encountered
b) By maintaining a certain degree of workability, but at a lower water content, the concrete strength can be increased without further cement addition
c) While maintaining the same w/c ratio and processability, the concrete can be brought to a given strength, such as the lower cement content of the reference concrete.
Impact on durability
The direct addition of this type of mixture does not increase the permeability, and in fact the permeability is significantly reduced in the case where the mixture is used to reduce w / c.
Effect on shrinkage
When used as a workability aid for water reducing agents, this type of mixture does not adversely affect shrinkage. Application of water reducing concrete admixture
The application of the admixture type is as follows -
a) When concrete pouring is limited due to crowded steel bars or these parts.
b) A mixture produced, for example, with aggregate (crushed) when a rough mixture is encountered. A significant improvement in concrete plasticity can then be obtained.
c) When it is difficult to obtain the required strength in the case of the specified maximum cement content and the need to increase the strength in advance.
d) By adding this mixture to the concrete, an economy of about 10% can be obtained.
Slow concrete admixture
The effect of delaying the concrete admixture is to delay or prolong the setting time of the cement slurry in the concrete. These are helpful for concrete that must be transported over long distances in a transport mixer and that help to place the concrete at elevated temperatures, particularly as a grouting mixture and water reducer resulting in an increase in strength and durability.
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