What are the characteristics of limestone?

Answer 1

Chemical composition:

limestone is composed of various minerals (a material made up of a combination of atoms of various elements arranged in a specific atomic lattice to form crystals - as they are a mixture of varying elements they may also be referred to as compounds). The most common of which in Limestone is Calcite / Calcium Carbonate.

Calcium Carbonate has the chemical formula CaCO3. From this we can see that limestone is formed predominantly from the elements Calcium (Ca), Carbon (C) and Oxygen (O).

A type of limestone known as dolomite is composed of calcium magnesium carbonate CaMg(CO3)2 .

Density:

The density of limestone is very variable as it is a natural earth material. As such, a range of densities are quoted in the literature and testing should be done on a specific sample to get an exact result.

Range of intact densities for limestone:

Common - 2100 to 2610 kg/m3[A] and occasionally up to 2900 kg/m3[B]

In imperial units:

131.1 lbs/ft3 to 162.9 lbs/ft3 and occasionally up to 181.0 lbs/ft3.

Elastic Modulus:

Intact Limestone can have a Young's modulus (E) ranging from:

9 GPa - 80 GPa.A,B

Poisson's ratio (v) for intact specimens varies from between:

0.2 - 0.3.B

Bulk modulus (K) derived from the above values using the following relation:

K = E / (3(1-(2v))

Bulk Modulus ranges from:

5 GPa - 66.67 GPa

Shear modulus (G) derived from the above values using the following relation:

G = E / 2(1+v)

Shear modulus ranges from:

3.5 GPa to 33.33 GPa

Uniaxial Compressive Strength:

Intact Limestone can have a uniaxial compressive strength ranging from:

15 MPa - 290 MPa.A,B

Sources:

[A] Bell, F. G. (2007). Basic Environmental and Engineering Geology. Dunbeath, Whittles Publishing Limited.

[B] Cobb, F. (2009). Structural Engineer's Pocket Book, Second edition. London, Butterworth-Heinemann.