The initial compressive strength of concrete into that retarding admixtures are added is lower than the compressive strength of a similar concrete that wasn't treated with retarding admixtures.
Retarding admixtures don't reduce the heat output of concrete however delay the rise of the peak temperatures by a time interval much like the one where the concrete was retarded.
Retarding admixtures do not normally entrain air but there are some kinds of retarders that do. Especially these based on hydroxycarboxylic acid can actually reduced air content.
Air entraining admixtures are often utilized to improve the freeze-thaw resistance of concrete. After the water from the concrete starts freezing, the air cells function as microscopic expansion chambers to the freezing water.
Retarding admixtures extend the setting time of concrete and maintain the workability and cohesion for an extended period of time.
From the large construction projects, concrete retarder prevents cold joints formation in successive lifts and make concretely workable through concrete placing.
With the usage of concrete retarders, you can compensate for the accelerating effect of high temperature towards the initial setting time and minimize risks of long-distance delivery in warm weather.
The usage of retarding admixtures improves the permeability of concrete by delayed setting period and improved workability of concrete.
Concrete retarders help to reduce segregation and bleeding in concrete where poor sand grading is unavoidable.
The concrete retarders may be employed with water-reducers however care needs to be taken while curing to avoid bleeding and cracks.
The dosage of retarding admixtures must be within limits based upon its water-cement ratio, cement content, and amount of C3A from the cement.
Use of gypsum as a retarding admixture for the purpose of retarding setting time is recommended when adequate control and inspection can be obtained, otherwise, the addition of excess amount can cause undesirable expansion and an indefinite delay in the setting of concrete.
Concrete retarders could have variable action on different kinds of cement when used in different quantities.
Retarding admixtures are most commonly used in hot weather concreting.
Retarder Concrete sprayed to the surface of the formwork to prevent the hardening of this matrix in the interface of concrete and formwork, whereas the rest of the concrete gets.
Retarders are utilized for large or massive construction work hardened.
Retarding admixtures are used in grouting oil wells.