Concrete Essential - All about concrete in brief

A PowerPoint briefly discussing on the essential aspects of concrete manufacture highlighting on its uses and the importance of each of its constituents

1. UNIVERSITY OF MAURITIUS
BENG CIVIL ENGINEERING LEVEL 2
C O NCRETE
E S S E N T I A L S
TUTORIAL 4
Felicité Grégorie
Submitted to Mr DoomahM. Z.
19
TH
December 2022

2. What is concrete
A mixture of aggregates (sand, gravel or crushed stone)
held by a cement paste which consists of cement and water.
It is regarded as one of the most reliable building materials ever.
Concrete's potential has yet to be fully realised
due to the countless uses it may be put to.
HOMES PAVEMENTS PARKING FACILITIES ROADS
1

3. CEMENT
What is cement
Importance of cement
A powdery substance which acts as a binder to aggregates,
in contact with water, to form concrete.
Initially in a fluid state, the binding agent together with the other components of
concrete, then hardens and set.
The main ingredients of cement are limestone and clay, *SCMs are added as
admixtures as well.
Workability
Compressive strength
Drying shrinkage
Durability
2

4. AGGREGATES
What are aggregates
As important as cement in the production of concrete, they
highly affect the properties (fresh and hardened) of the latter.
Aggregates should be quantitatively and qualitatively chosen in
accordance to the construction being.
Importance of aggregates
Lower the amount of cement to be used (economic benefits)
Better durability & volume stability can be achieved
Do not chemical interfere with mixture composition
Relatively cheap construction material
NOTE : 60 to 75 % of concrete volume & 70 to 85 % of concrete weight
CRUSHED STONE
SAND
GRAVELS
3

5. WATER
Role of water
Volume Ratio
The fine grains of cement start to float about in the water and dissolve.
Ions in cement make new combinations to form a precipitation of
hydrates (solid paste).
By holding the grains together, the precipitate creates a rigid solid
at the end with a higher volume.
The process is termed as hydration.
Cement ratio for concrete is 0.4
(for each gram of cement 0.4 gram of water is added).
Increasing or lowering this ratio impacts on permeability,
porosity, strength and durability.
20% of the water remains as pores in the cement paste (or concrete).
During this reaction, heat is considerably evolved.
Texture of cement before addition of water
Texture of cement after addition of water
4

6. STRENGTH
Strength of Concrete
The quality of concrete is mostly based on itsstrength.
Concrete is under the effect of flexural and tensile forces but we are mostly concerned with
its compressive strength.
Compressive strength is a measure used to access the performance of a concrete mixture..
Considering this aspect of concrete is important because it is the primary measure
determining how well concrete can withstand loads that affect its size.
0.01 0.1 1.0 10 100
40
50
60
50 years
Compressive Strength (N/mm²)
Age (year)
Compressive strength variation with time (Washa and Wendt -1989)
The compressive strength relatively increases with ages.
Necessary strength for practical use is achieved in 28 days.
During this reaction, heat is considerably evolved.
5

7. STRENGTH
Factors affecting Strength of Concrete
Cement type
Cleanliness and grading of the aggregates
Water to cement ratio
Presence of admixtures
Handing and placing methods
Concrete Mixing
6

8. Why concrete
126 A.D, Pantheon, Rome
STRENGTH
1853, St Denis, France
ENDURANCE
2012, Clover House, Ecuador
DESIGN FLEXIBILITY
Fire in 2019, Notre Dame Cathedral, France
RESILIENCE
1830 -1840, Fort Adelaide, Port-Louis Mauritius
HISTORICAL ASSETS
7

9. C NCRETE
E S S E N T I A L S
THANK YOU