What are the major reasons by using admixture in concreting?

The major reasons for using admixtures are

 Reduceing the cost of concrete construction and achieve certain properties in concrete more effectively than by other means also maintain the quality of concrete during the stages of mixing, transporting, placing, and curing in adverse weather conditions & overcome certain emergencies  during concreting operations

when we say admixture, it does not mean Plasticiser, any thing added to concrete other than Cement, Aggregate, Sand and Water is termed as admixture..

Depending on the required properties of concrete, type or kind of admixture is decided.. for example, we need to use accelerator for early setting and retarder to delay the initial setting time of concrete..

Selection of admixture shall be done by performing trials and checking the compatibility of admixture with concrete. 

One of the major reason for using admixtures is to improve the consistency and workability of fresh concrete during mixing, transporting and placing, especially in hot weather concreting

• Admixtures are used to maintain the quality of concrete at every stage of the production process.
• It is also used to reduce production cost of concrete.
• Also used to improve/enhance overall performance of concrete.

Admixtures are the backbone of modern concrete system.Hence, are responsible for the achievement of high performance concrete.Major reason of adding admixture in concrete is to enhance fresh concrete,mechanical properties and durability properties of concrete, while decreasing the consumption of cement as its production is responsible for increase in carbon imprints.

By using admixture concrete could have dense cement paste matrix.More dense the micro-structure may be less vulnerable will be the concrete to deteriorating agents and more will be the service life of the concrete.Less probability of sulfate attack,Alkali aggregate reactions and other durability problems to occur.

Producers use admixtures primarily to reduce the cost of concrete construction; to modify the properties of hardened concrete; to ensure the quality of concrete during mixing, transporting, placing, and curing; and to overcome certain emergencies during concrete operations. 

Concrete admixtures are used to improve the behavior of concrete under a variety of conditions. Chemical admixtures reduce the cost of construction, modify properties of hardened concrete, ensure quality of concrete during mixing, transporting, placing, curing, and overcome certain emergencies during concrete operations. Chemical admixtures are used to improve the quality of concrete during mixing, transporting, placement and curing. They fall into the following categories:air entraining, water reducers, set retarders, set accelerators, superplasticizers, specialty admixtures: which include corrosion inhibitors, shrinkage control, alkali-silica reactivity inhibitors, and coloring. Mineral addmixtures make mixtures more economical, reduce permeability, increase strength, and influence other concrete properties. Mineral admixtures affect the nature of the hardened concrete through hydraulic or pozzolanic activity. 

Usually admixture or combination different admixtures are used to maintain special properties of fresh and hardened concrete. The main function of using admixture in concrete is to enhance the workability of fresh concrete and durability criteria of hardened concrete as well.

In normal way admixtures are used to reduce the difficulties in handling concrete at site (Transportation, placement, pumpablility, early setting time and high early strength etc.)

 Admixture is also used to optimize the cement composition to make the concrete sustainable.

The main function of using admixture is to increase strength and decrease water concrete without increasing cement concrete 

Usually we use different types of admixturer

• High range water reducer (HRWR) Type F and Type G
•  Accelerator (Type E and Type C) reduce initial setting time and increase high early strength of concrete 
• Retarder (Type B and Type D) use to make the concrete setting time delay in hot weather and when sending concrete at long distance.
• Water Reducer Type A admixture making high slump without increasing water content in plastic concrete. 
• Air Entering admixture use where freezing and thawing condition exist but around5% decrement in strength take place after every1% air added in concrete.

For increasing setting time to avoid concrete expiring when placement of concrete is difficult in a circumstance etc