Brief Introduction of Concrete Technology. Pre-requisite for understanding the material science and basic knowledge for concrete mixing.

1. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
By
Prof DEEPAK PATIL
MODULE- I

2. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
AGGREGATES
• Aggregates are the important constituents in concrete.
• They give body to the concrete, reduce shrinkage and effect economy.
• Aggregates occupy 70–80 per cent of the volume of concrete.
• Aggregates impact on various properties of fresh concrete as well as
hard concrete.

3. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
CLASSIFICATION OFAGGREGATES
1) Based on Weight
Normal Weight Concrete
Light Weight Concrete
Heavy Weight Concrete
2) Based on Source of occurrence
Natural Aggregates:- Sand Gravel, Crushed Rocks such as Granite, Quartzite, Basalt, Sandstone
Artificial Aggregates:- Broken bricks, Air-cooled slag, Sintered fly ash, Bloated clay
3) Based on size of aggregates
Coarse aggregates:-The size of aggregate bigger than 4.75 mm is considered as coarse aggregate
Fine aggregates:- aggregate whose size is 4.75 mm and less is considered as fine aggregate.

4. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
4) Based on Shape of aggregates
a) Angular aggregates exhibit a better interlocking effect in concrete, which property makes it superior in
concrete used for roads and pavements.
b) The total surface area of rough textured angular aggregate is more than smooth rounded aggregate for
the given volume. By having greater surface area, the angular aggregate may show higher bond strength
than rounded aggregates.

5. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

6. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

7. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

8. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

9. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
PHYSICAL PROPERTIES OG AGGREGATES
1)Size
2)Shape
3)Texture
4)Specific Gravity
5)Absorption and Moisture Content
6)Strength
Aggregate Crushing Strength
Aggregate Impact Value
Aggregate abrasion value
Modulus of Elasticity

10. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Aggregate Crushing Test

11. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Aggregate Impact Value Test

12. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Aggregate Abrasion Value Test

13. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Modulus of Elasticity of aggregates
Modulus of elasticity of aggregate depends on its composition, texture and structure. The modulus of elasticity of
aggregate will influence the properties of concrete with respect to shrinkage and elastic behavior and to very small
extent creep of concrete.

14. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

15. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Bulking of Aggregates
The free moisture content in fine aggregate results in bulking of volume. Bulking phenomenon can be explained as
follows:
 Free moisture forms a film around each particle.
 This film of moisture exerts what is known as surface tension which keeps the neighboring particles away from it.
 Similarly, the force exerted by surface tension keeps every particle away from each other.
 Therefore, no point contact is possible between the particles. This causes bulking of the volume.
 The extent of surface tension and consequently how far the adjacent particles are kept away will depend upon the
percentage of moisture content and the particle size of the fine aggregate.
 It is interesting to note that the bulking increases with the increase in moisture content up to a certain limit and
beyond that the further increase in the moisture content results in the decrease in the volume and at a moisture
content representing saturation point, the fine aggregate shows no bulking.

16. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

17. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Water

18. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
Water is an important ingredient of concrete as it actively participates in
the chemical reaction with cement.
It helps to form the strength giving cement gel.
The quantity and quality of water is required to be looked into very
carefully.
A popular yard-stick to the suitability of water for mixing concrete is that,
if water is fit for drinking it is fit for making concrete

19. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022

20. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022
The following guidelines should also be taken into consideration regarding the quality
of water.
(a)To neutralize 100 ml sample of water using phenopthaline as an indicator, it should
not require more than 5 ml of 0.02 normal NaOH.
(b)To neutralize 100 ml of sample of water, using mixed indicator, it should not require
more than 25 ml of 0.02 normal H2SO4.
(c)Permissible limits for solids is as given below in table 4.2.

21. MGMU’s JNEC Civil Engineering Department Prof DEEPAK PATIL Subject: Concrete Technology Date : 19.3.2022