Technical - Concrete admixture as per IS 9103

Admixtures for the concrete can be classified as follows as per functions:
(Reference ASTM C 494 or AASHTO M 194)
Type A - water reducing admixture.
Type B - retarding admixture
Type C - Accelerating admixture
Type D - Type A + Type B
Type E - Type C + Type D
Type F - Superplactizier (high range water reducer)
           As per ASTM C 1017Plasticizers for Flowing Concrete is known as Superplasticizers
                 Type 1 - Plasticizing
                 Type 2 - Plasticizing and retarding
Type G - Type F + Type B

Let us go in detail:
1. Air-entraining admixtures: entraining air in the concrete for providing resistance to freezing and thawing action
2. Water-reducing admixtures: that reduce the water demand for a given workability.
Water reducers are classified broadly into two categories: 
       (1) Normal range - The normal water reducers are also called ‘plasticizers’ reduce the water demand by 5 – 10%. Ex: Lignosulphonate salts of sodium and calcium, hydroxycarboxylic acids (citric and gluconic acid) and carbohydrates (corn syrup and dextrin) based are of normal water reducers. 
         (2) High range -  The high range water reducers are called ‘superplasticizers’ can cause a reduction of 15 – 40%.

All the superplasticizers are water soluble polymers. As for other polymers, the behaviour of superplasticizers is also a function of the structure and the degree of polymerization.

Lignosulphonates are generally regarded as ‘1^st generation’ superplasticizers, 
Sulphonated formaldehyde condensates are called ‘2^nd generation’
Polycarboxylates and polyacrylates are termed as 3^rd generation superplasticizers. 

Currently, the most widely used superplasticizers are the sulphonated formaldehyde condensates. However, the beneficial effects of polycarboxylates are ensuring a gradual shift towards these chemicals.

3. Accelerating admixtures: that control the setting time and strength gain rate of concrete
4. Retarding admixtures
5. Hydration-control admixtures
6. Corrosion inhibitors
7. Shrinkage reducers
8. Alkali-silica reactivity inhibitors
9. Coloring admixtures
10. Miscellaneous admixtures such as workability, bonding, dampproofing, permeability reducing, grouting, gas-forming, anti-washout, foaming, and pumping admixtures

The major reasons for using admixtures are:

1. To reduce the cost of concrete construction

2. To achieve certain properties in concrete more effec- tively than by other means

3. To maintain the quality of concrete during the stages of mixing, transporting, placing, and curing in ad- verse weather conditions

4. To overcome certain emergencies during concreting operations

Let see the type of admixture, what effect they give and which are the material - chemical used in:

Type of admixture	Desired effect	Material
Accelerators (ASTM C 494 and AASHTO M 194, Type C)	Accelerate setting and early-strength development	Calcium chloride (ASTM D 98 and AASHTO M 144) Triethanolamine, sodium thiocyanate, calcium formate, calcium nitrite, calcium nitrate
Air detrainers	Decrease air content	Tributyl phosphate, dibutyl phthalate, octyl alcohol, water- insoluble esters of carbonic and boric acid, silicones
Air-entraining admixtures (ASTM C 260 and AASHTO M 154)	Improve durability in freeze-thaw, deicer, sulfate, and alkali- reactive environments Improve workability	Salts of wood resins (Vinsol resin), some synthetic detergents, salts of sulfonated lignin, salts of petroleum acids, salts of proteinaceous material, fatty and resinous acids and their salts, alkylbenzene sulfonates, salts of sulfonated hydrocarbons
Alkali-aggregate reactivity inhibitors	Reduce alkali-aggregate reactivity expansion	Barium salts, lithium nitrate, lithium carbonate, lithium hydroxide
Antiwashout admixtures	Cohesive concrete for underwater placements	Cellulose, acrylic polymer
Bonding admixtures	Increase bond strength	Polyvinyl chloride, polyvinyl acetate, acrylics, butadiene-styrene copolymers
Coloring admixtures (ASTM C 979)	Colored concrete	Modified carbon black, iron oxide, phthalocyanine, umber, chromium oxide, titanium oxide, cobalt blue
Corrosion inhibitors	Reduce steel corrosion activity in a chloride-laden environment	Calcium nitrite, sodium nitrite, sodium benzoate, certain phosphates or fluosilicates, fluoaluminates, ester amines
Dampproofing admixtures	Retard moisture penetration into dry concrete	Soaps of calcium or ammonium stearate or oleate Butyl stearate Petroleum products
Foaming agents	Produce lightweight, foamed concrete with low density	Cationic and anionic surfactants Hydrolized protein
Fungicides, germicides, and insecticides	Inhibit or control bacterial and fungal growth	Polyhalogenated phenols Dieldrin emulsions Copper compounds
Gas formers	Cause expansion before setting	Aluminum powder
Grouting admixtures	Adjust grout properties for specific applications	See Air-entraining admixtures, Accelerators, Retarders, and Water reducers
Hydration control admixtures	Suspend and reactivate cement hydration with stabilizer and activator	Carboxylic acids Phosphorus-containing organic acid salts
Permeability reducers	Decrease permeability	Latex Calcium stearate
Pumping aids	Improve pumpability	Organic and synthetic polymers Organic flocculents Organic emulsions of paraffin, coal tar, asphalt, acrylics Bentonite and pyrogenic silicas Hydrated lime (ASTM C 141)
Retarders (ASTM C 494 and AASHTO M 194, Type B)	Retard setting time	Lignin Borax Sugars Tartaric acid and salts
Shrinkage reducers	Reduce drying shrinkage	Polyoxyalkylene alkyl ether Propylene glycol
Superplasticizers* (ASTM C 1017, Type 1)	Increase flowability of concrete Reduce water-cement ratio	Sulfonated melamine formaldehyde condensates Sulfonated naphthalene formaldehyde condensates Lignosulfonates Polycarboxylates

Superplasticizer* and retarder (ASTM C 1017, Type 2)	Increase flowability with retarded set Reduce water–cement ratio	See superplasticizers and also water reducers
Water reducer (ASTM C 494 and AASHTO M 194, Type A)	Reduce water content at least 5%	Lignosulfonates Hydroxylated carboxylic acids Carbohydrates (Also tend to retard set so accelerator is often added)
Water reducer and accelerator (ASTM C 494 and AASHTO M 194, Type E)	Reduce water content (minimum 5%) and accelerate set	See water reducer, Type A (accelerator is added)
Water reducer and retarder (ASTM C 494 and AASHTO M 194, Type D)	Reduce water content (minimum 5%) and retard set	See water reducer, Type A (retarder is added)
Water reducer—high range (ASTM C 494 and AASHTO M 194, Type F)	Reduce water content (minimum 12%)	See superplasticizers
Water reducer—high range—and retarder (ASTM C 494 and AASHTO M 194, Type G)	Reduce water content (minimum 12%) and retard set	See superplasticizers and also water reducers
Water reducer—mid range	Reduce water content (between 6 and 12%) without retarding	Lignosulfonates Polycarboxylates

Superplasticizers are also referred to as high-range water reducers or plasticizers. These admixtures often meet both ASTM C 494 (AASHTO M 194) and ASTM C 1017 specifications.

IS:9103 is the only Indian Standard Specification on admixtures for concrete covers the accelerating admixtures, retarding admixtures, water reducing admixtures, and air entertaining admixtures.

These admixtures have been defined in brief with their physical requirements including the methods of sampling of admixtures for test and preparation of test samples of concrete with admixtures.

For information on IS 2645, refer to post “IS 2645 INTEGRAL WATERPROOFING COMPOUNDS”.

Many thanks to google.com and doc88.com from where the details have been collected.