FAQ's
1. What is admixture ?
An admixture is a material added to concrete during mixing to modify its properties. Admixtures can alter characteristics such as workability, setting time, strength, durability, and resistance to adverse conditions.
2. What is the role of admixture in concrete?
Admixtures play a crucial role in enhancing the performance and versatility of concrete. They help achieve desired properties, improve workability, reduce water content, control setting time, enhance strength and durability, and optimize concrete for specific applications.
3. How many types of admixture as per IS 9103?
5 types: Accelerating Admixtures, Retarding Admixtures, Water-Reducing, Admixtures Air-entraining Admixtures, Super Plasticizing Admixtures-> a. Retarding Type b. Normal Type
4. How many types of admixture as per ASTM C494?
Type A – Water Reducing Admixtures Type B – Retarding Admixtures Type C – Accelerating Admixtures Type D – Water Reducing and Retarding Type E – Water Reducing and Accelerating Type F – Water Reducing, High Range Type G – Water Reducing, High Range and Retarding Type S – Specific Performance Admixtures
5. Does an admixture give strength?
While admixtures can indirectly contribute to the strength of concrete by improving its overall quality and performance, their primary function is to modify properties such as workability, setting time, and durability. Admixtures alone do not provide strength but can optimize concrete mixtures for higher strength potential.
6. What admixture increases the setting time of concrete?
Retarding admixtures, such as Type B admixtures according to ASTM C494 or Type II admixtures according to IS 9103, are used to increase the setting time of concrete. They slow down the hydration process, allowing more time for placement and finishing.
7. How to inspect the good quality of admixture?
The quality of admixture can be inspected by checking its compliance with relevant standards, reviewing manufacturer's technical data sheets, verifying batch-to-batch consistency, performing compatibility tests with concrete materials, and ensuring proper labeling and packaging.
8. Effect of admixture on the properties fresh concrete?
Admixtures can have various effects on fresh concrete properties, including improved workability, reduced water content, increased slump, enhanced cohesiveness, better pumpability, and reduced segregation and bleeding.
9. Effect of admixtures on the properties hardened concrete?
Admixtures can influence the properties of hardened concrete by enhancing strength development, improving durability, reducing permeability, minimizing shrinkage and cracking, increasing resistance to chemical attacks, and enhancing surface finish and aesthetics.
10. Difference between plasticizer & superplasticizer?
Plasticizers and superplasticizers are both types of water-reducing admixtures. However, they differ in their effectiveness and dosage rates. Plasticizers typically provide moderate water reduction and improve workability, while superplasticizers offer higher water reduction and greater flowability without increasing water content. Superplasticizers are often used when high levels of workability and slump retention are required.
11. How is the slump of Readymix Concrete controlled, and what does it signify?
The slump is controlled by adjusting the water and admixture content in the mix. It measures the consistency and workability of concrete; a higher slump indicates a more fluid mix.
12. What is the role of admixtures in RMC production?
Admixtures are used to enhance specific properties of concrete, such as setting time, durability, and workability. They are carefully selected based on the desired characteristics of the final product.