Concrete

This deck is about concrete

What is specific heat of an aggregate?

The specific heat of an aggregate is the amount of heat required to raise the temperature of a unit mass of the aggregate by one degree Celsius. It influences the thermal performance of concrete in construction.
In simple terms, it is a measure of its heat capacity.

What is thermal conductivity of an aggregate?

Measure of its ability to conduct heat.

Effect of thermal expansion

breaks the bond between the aggregate and the paste.

Durability of concrete is affected by the following

1) Differences in thermal expansion of two different materials.

Factors on which the length of time for which a concrete mixture will remain plastic depends upon

1) The amount of mixing water used

2) Atmospheric temperature

It depends on these 2 more than on the setting time of cement.

What is setting time of cement?

Initial Setting Time

• Definition: The time elapsed from when water is added to the cement until the paste starts losing its plasticity and stiffness.

Final Setting time

• Definition: The time elapsed from when water is added until the cement paste completely loses its plasticity and transforms into a hard mass.

Advantages of using pozzolana as an admixture in concrete

• Improves workability with lesser amount of water

• It increases resistance to attack by salts and sulphates

What is workability of concrete ?

The workability of concrete is the ease with which fresh concrete can be mixed, transported, placed, compacted, and finished without losing homogeneity, bleeding, or segregation