This document discusses different types of concrete admixtures, including air entraining admixtures, plasticizers, superplasticizers, retarders, accelerators, and coloring admixtures. Concrete admixtures are added to concrete mixes to impart desirable properties. Air entraining admixtures introduce tiny air bubbles that increase frost and scaling resistance. Plasticizers and superplasticizers reduce the water content needed for workability or increase workability at the same water content. Retarders slow hydration for longer workability, while accelerators speed strength development. Coloring admixtures are used for aesthetics and safety. Admixtures can modify properties like workability, strength, permeability and curing time.

1. CONCRETE
ADMIXTURES
SUBMITTED BY-VIDHI
SINGH
B.TECH 4th yr
CIVIL ENGG.

2. CONTENTS
 INTRODUCTION
 CONCRETE ADMIXTURES
 WHY CHEMICAL ADMIXTURES?
 IMPORTANT CHEMICAL ADMIXTURES
 AIR ENTRAINING ADMIXTURES
 PLASTICIZERS (WATER REDUCERS)
 SUPERPLASTICIZERS (HIGH RANGE WATER
REDUCERS)
 RETARDERS
 ACCELERATORS
 COLORING ADMIXTURES
 CONCLUSON

3. INTRODUCTION
Admixtures are the material, other than
 Cement
 Water
 Aggregates
Which are used as an ingredient of concrete and is
added to batch immediately before or during mixing.
Admixtures are normally provided as water based
solutions and can be added to the concrete at upto
5% on cement weight.

4. CONCRETE ADMIXTURES
 A chemical added to the concrete at the time of
mixing to impart desirable behaviour.

5. WHY CHEMICAL ADMIXTURES?
 Produce desire effect.
 To make a poor concrete better.
 When properties cannot be made by varying the
composition of basic material.
 To overcome certain emerencies during concretin
operation.

6. IMPORTANT CHEMICAL ADMIXTURES
 Air entraining admixtures
 Plasticizers
 Super plasticizers
 Retarders and Retarding Plasticizers
 Accelerators and Accelerating Plasticizers
 Coloring admixtures
 Damp-proofing and Waterproofing Admixtures
 Fungicidal, Germicidal, Insecticidal Admixtures

7. AIR ENTRAINING ADMIXTURES
 It introduce and stabilize microscopic air bubbles in
concrete.
Scaling due to lack of air.

8. AIR ENTRAINING ADMIXTURES
The following types of air entraining agents are used
for making air entrained concrete.
 Natural wood resins
 Animal and vegetable fats and oils, such as tallow,
olive oil and their fatty acids such as stearic and
oleic acids.
 Various wetting agents such as alkali salts or
sulphated and sulphonated organic compounds.

9. PLASTICIZERS (WATER REDUCERS)
 The organic substances or combinations of
organic and inorganic substances, which
allow a reduction in water content for the
given workability, or give a higher workability
at the same water content, are termed as
plasticizing admixtures.

10. USED AT-PLASTICIZERS
(WATER REDUCERS)

11. SUPERPLASTICIZERS (HIGH RANGE
WATER REDUCERS)
 Superplasticizers constitute a relatively new
category and improved version of
plasticizer, the use of which was developed
in Japan and Germany during 1960 and
1970 respectively. They are chemically
different from normal plasticisers.

12. CLASSIFICATION OF SUPERPLASTICIZERS
1. Sulphonated malanie-formaldeyde condensates
(SMF)
2. Sulphonated napthalene-formaldehyde
condensates (SNF)
3. Modified lignosulphonates (MLS)

13. SUPERPLASTICIZERS (HIGH RANGE
WATER REDUCERS)
Superplasticizers is practised for -
 Production of flowing, self levelling, self compacting
concrete
 Production of high strength and high performance
concrete.

14. RETARDERS
A retarder is an admixture that slows down the
chemical process of hydration so that concrete
remains plastic and workable for a longer time than
concrete without the retarder.
Retarders are used to overcome the accelerating
effect of high temperature on setting properties of
concrete in hot weather concreting.

15. RETARDERS
USED AT-
 Casting and consolidating large
number of pours without the
formation of cold joints.
 Grouting oil wells, where temperature
is about 200 °C, at a depth of 6000
meters.

16. ACCELERATORS
Accelerating admixtures are added to concrete to
increase the rate of early strength development.
Why accelerators?
 Permit earlier removal of formwork
 Reduce the required period of curing
 Advance the time that a structure can be placed in
service
 In the emergency repair work.

17. ACCELERATORS
Commonly used materials as an
accelerator:
 Calcium chloride (Not used now)
 Some of the soluble carbonates
 Silicates fluosilicates (Expensive)
 Some of the organic compounds such as
triethenolamine (Expensive)

18. COLORING ADMIXTURES
Natural and synthetic materials are used to color
concrete for aesthetic and safety reason.

19. CONCLUSION
Overviews of the conclusion by using admixtures in
concrete are-
 Increase workability without increasing water content or
decrease the water content at same workability.
 Retard or accelerate time of initial setting.
 Reduce or prevent shrinkage.
 Modify the rate or capacity for bleeding.
 Reduce segregation.
 Reduce rate of slump loss.
 Increase bond of concrete to steel reinforcement.
 Decrease permeability of concrete.

21. QUERIES???