What are the main types of admixtures covered in IS 9103?

Water-reducing (plasticizers), high range water-reducing (superplasticizers), retarding, accelerating, and combination admixtures like retarding-water reducing (Clause 4).

What is the maximum permissible chloride content in admixtures for RCC?

0.05 percent by mass of the admixture for reinforced or prestressed concrete (Table 2).

What is the minimum compressive strength requirement at 28 days for concrete with a superplasticizer?

The compressive strength should be at least 100% of the reference (control) concrete mix strength (Table 1).

How much can a retarding admixture delay the initial setting time of concrete?

It should delay the initial set by at least 60 minutes but not more than 360 minutes compared to the control mix (Table 1).

IS 9103

: 1999

Admixtures for Concrete - Specification

CurrentFrequently UsedSpecificationBIMMaterials Science · Concrete

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This standard specifies the requirements for seven types of chemical admixtures for concrete, such as plasticizers, superplasticizers, and retarders. It covers material classification, physical and chemical performance criteria, testing procedures, and marking instructions to ensure the quality and uniformity of admixtures used in construction.

Specifies requirements for chemical admixtures to be used in concrete to modify its properties.

Quick Reference Values

Minimum water reduction for Normal Water-Reducing Admixtures5 percent

Minimum water reduction for Superplasticizers20 percent

Maximum chloride ion content for reinforced/prestressed concrete0.05 percent by mass of admixture

Initial setting time delay for Retarding AdmixturesMinimum 60 minutes

Maximum initial setting time delay for Retarding AdmixturesMaximum 360 minutes

Minimum 1-day compressive strength for Accelerating Admixtures125 percent of control

Minimum 7-day compressive strength for Superplasticizers140 percent of control

Practical Notes

Always conduct compatibility tests between the specific cement, aggregates, and admixture before mass use, as performance can vary significantly.

Strictly adhere to the manufacturer's recommended dosage. Overdosing can cause severe segregation and bleeding, while underdosing fails to achieve desired effects.

Pay close attention to the chloride content of the admixture (Table 2), especially for reinforced and prestressed concrete, to prevent long-term rebar corrosion.