Through this presentation you can know about the factors which effects the strength of concrete. Thanks.

1. LOGO
FACTOR EFFECTING THE STRENGTH OF
CONCRETE

2. 
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Water/cement ratio: this is defined as the mass of water
divided by the mass of cement in a mix. For example, a
concrete mix containing 400 kg cement and 240 litres
(=240 kg) of water will have a water/cement ratio of
240/400=0.6. The water/cement ratio may be
abbreviated to 'w/c ratio' or just 'w/c'. In mixes where the
w/c is greater than approximately 0.4, all the cement
can, in theory, react with water to form cement hydration
products. At higher w/c ratios it follows that the space
occupied by the additional water above w/c=0.4 will
remain as pore space filled with water, or with air if the
concrete dries out.
Consequently, as the w/c ratio increases, the porosity of
the cement paste in the concrete also increases. As the
porosity increases, the compressive strength of the
concrete will decrease.
Factors affecting concrete strength

3.  Soundness of aggregate: it will be obvious that
if the aggregate in concrete is weak, the
concrete will also be weak. Rocks with low
intrinsic strength, such as chalk, are clearly
unsuitable for use as aggregate.
 Aggregate-paste bond: the integrity of the
bond between the paste and the aggregate is
critical. If there is no bond, the aggregate
effectively represents a void; as discussed
above, voids are a source of weakness in
concrete.
Factors affecting concrete strength

4. Effect Of Temperature
• Low temperature decreases the early
strength development.
High temperature at early stage:
• Increase the early strength
• Decrease the ultimate strength

5. Effect of Humidity
• Moisture creates the ideal conditions for
the growth of mold, mildew and bacteria.
When mold and bacteria grow and
reproduce within concrete, they affect its
strength.
• When relative humidity levels increase,
the compressive strength of concrete
decreases, affecting its durability.

6. Effect of compaction
• Compaction of concrete is very important in
developing qualities like strength, durability.
Imperviousness by making the concrete
dense and free from voids.
• It is done by vibrator mostly.
• If full compaction is not achieved , porous
and honey-combed concrete will produced
resulting in loss of strength.

7. Curing
Positive effects:
• Protects concrete surface from sun and wind.
• The presence of water is essential to cause the
chemical action which accompanies the setting of
concrete.
• Resistance of concrete to abrasion is increased.
• By proper curing durability is increased and shrinkage is
reduced.

8. Curing
Negative effects :
• Compressive strength is reduced.
• Cracks will be formed due to shrinkage.
• Durability decreases
• Frost and weathering resistance are decreased.
• Rate of carbonation increases