Foundation, Concrete and Earthquake Engineering

Comparison of Thermal Expansion of No-fines Concrete with Normal Concrete

Thermal properties of any type of concrete like thermal conductivity, thermal diffusivity and thermal expansion are considered in concrete design and construction due to following reasons:

a. Thermal strains

b. Warping

c. Cracking

d. To have idea about temperature gradient

e. Providing joints in concrete say expansion joints and contraction joints.

Here our concern is about thermal expansion and we were discussing about no-fines concrete. Here this property will be compared with normal concrete. So we should have idea about thermal expansion of normal concrete.

The co-efficient of thermal expansion depends on

  • Mix composition

  • Hygral state during temperature change

In following table we are providing thermal expansion after 2 years in relation to aggregate content in concrete.
Thermal expansion of concrete in relation to aggregate content
The linear coefficient for thermal expansion of normal concrete is 6.67X10-6 per0F and volumetric coefficient for thermal expansion of normal concrete is 20X10-6 per 0F. (Both are at 200C).

Now come to the point no-fines concrete; the coefficient of thermal expansions for this concrete are about (0.6-0.8) of thermal expansions of normal concrete both in linear and volumetric consideration.

But the true value of this coefficient depends on aggregate types that are chosen for concrete batching. This coefficient is very important in designing joints where concrete may suffer large movement under thermal action and significant structural damage may be incorporated with this expansion. Normally high rise buildings, bridge construction and in structurally indeterminate members they are very important.

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