Admixtures for Concrete
Concrete admixtures they are basically concrete ingredients which is other than water, Portland cement and aggregate which are added in mix very immediately before mixing. Mainly the producer's use admixtures for reducing the concrete construction cost, for modifying the basic properties of harden concrete; it also ensures the concrete quality during the process of placing, mixing, curing and transporting and also to overcome on certain kind of emergencies during the operations of concrete.
A successful admixture usage totally depends on appropriate concreting and batching methods. Maximum admixtures now days are supplied in the form of liquid which is ready-to-use which is usually added in concrete on jobsite or at plant. Certain kind of admixtures for example: expensive agents, pigments and pumping aids are usually used in very small amount and they are batched through hands from a premeasured container.
Admixtures effectiveness totally depends on various different aspects which include: temperature of concrete, type of cement, slump, mixing time, amount of cement, water content and temperature of air. The admixture concrete's chemistry is a bit complex topic and requires a depth knowledge and experience before adopt its usage. A general and very basic understanding of variety of concrete admixture is important for picking right one as per your needs. Based on functions the admixtures can be easily classified in five major categories. They are mentioned as follows:
Water Reducing Admixtures:
It is normally used to reduce the required content of water for concrete mixture approx. to 5-10%.
This helps in slowing down the setting rate of concrete, it is basically used for counteract the effect of accelerating hot weather on the setting of concrete.
It increases the early strength rate of development; it also reduces the required time for protection and proper curing, and it speeds up and starts the finishing operations.
It is very well known as a high range water reducer it's abbreviate is (HRWR) or also as plasticizers, it can easily reduces the content of water by approx. 12% to 30% and it is added to concrete with very low to a normal slump and added to water-cement ratio for making high-slump flowing of concrete. Flowing concrete it is basically a very high fluid but it is a workable type of concrete which can be easily placed with almost little or no compaction or vibration. Effect of super plasticizer lasts to approx. 30-60 minutes which vary on the dosage rate and the brand. It is followed by very rapid loss in the workability of concrete. At jobsite the main motive of adding superplasticizer is to avoid slump loss.
Corrosion Inhibiting Admixtures:
This kind of admixture is basically used to slow the reinforcing of steel in concrete.
- It is admixture for concrete which has water reducing properties.
- With the help of it dense, workable and durable, concrete is produced.
- Concrete admixtures help in reducing the content of cement to the particular required strength.
- It helps in gain early strength.
- Gives lower permeability and also improves the workability.
- It reduces the ratio of water cement almost up to 15%.
- It has very high workability retention.
- It provides moderate retardation in the concrete.
- It also produces the pump able concrete.
Standards Is : 9103-1999 and astm-c-494-86, type a & d.
Product Code : AP-30B