Additives vs. Admixtures

Main Difference

The main difference between additives and admixtures lies in the difference of time in which they are added to concrete or cement. Additives are added to cement during the manufacturing process to give new properties to cement and admixtures are added to concrete mixtures during the mixing process to give new properties to it.

Difference Between Additives and Admixtures

Comparison Chart

Additives vs. Admixtures

Additives are the chemical components added to other materials to improve their chemical and physical properties. Admixtures are those chemical components which are added to some other materials to give it enhanced chemical and physical properties. Additives may be food additives or any other substance that is added to something in the small quantities to improve or preserve it. Admixtures are the components added to a concrete mixture while mixing process. Additives are mixed with cement. Admixtures are mixed with the concrete. Additives have a different time for mixing in cement. They are being added to the cement while manufacturing. Admixtures also differ based on the time for them to add in the concrete. They are added to concrete before or during mixing. They are different additives which are classified as retarders, accelerators, dispersants, fluid loss control agents, etc. Different admixtures are also classified as plasticizers, air retaining admixtures, water-reducing admixtures, etc. Additives are used to increase or decrease the setting time of the concrete. Admixtures are used to attain the possible desired strength of the concrete by minimizing the use of fine aggregates proportion. Hence, the additive is those ingredients that are added to cement during the process of manufacturing of cement in any industry. Admixtures are those ingredients which are added to concrete during mixing and results in better workability of concrete while reducing the water-cement ratio and increasing strength. The additive is just material like carbon which is added to increase the strength. Admixture is a ready-made mixture of material.

What are Additives?

Additives are the chemical components which are added to cement during manufacturing for getting new properties for cement. The raw materials that are used in the manufacturing of cement are lime, alumina, silica and iron oxide. All of these materials are ground into a fine powder and are mixed and then roasted. Several chemical reactions will initiate that give the final chemical composition of cement by heating this mixture to about 1500^oC. Additives are added to modify the mixing, setting, or hardened properties. The additives contribute additional mineral oxides to the cement paste. Various additives are added to the cement while manufacturing to obtain desired properties. These are accelerators, retarders, and dispersants.

Functions

• Accelerators reduce cement settling time and speed up the development of compressive strength
• Retarders increase the cement settling time to give it sufficient time for slurry placement in deep wells
• Dispersants reduce the viscosity of cement, slurry and to ensure good mud removal during placement

What are Admixtures?

Admixtures are the chemical components that are added to concrete while mixing to get desired properties. Admixtures are the components added in concrete other than water, cement, and aggregates. They are added to cement immediately before or during the mixing of a concrete mixture. The term admixture refers to an ingredient other than water, cement, or fiber added to a cement mixture during the mixing process. Admixtures are added to intentionally entrain air, increase workability, adjust the strength, adjust settling time and reduce water requirement. Admixtures are also used to accelerate or retarded setting time of concrete.

Types

• Air entraining admixtures; some synthetic detergents, salts of wood resins, salts of petroleum acids
• Plasticizers
• Water-reducing admixtures; lignosulfonates, hydroxylated carboxylic acids
• Accelerating admixtures; calcium chloride, sodium thiocyanate
• Retarding admixtures; lignin, borax, sugars
• Corrosion inhibitors

Conclusion

Additives and admixtures are the ingredients added to cement and concrete to get more desired properties. Both are the chemical components with certain distinctions.