We use natural stones for their natural beauty and timeless appeal. Apart from these, natural stones have some physical and chemical properties that are rendering them the most sought after material in the construction industry for centuries. Today, we are going to exploit one of those properties, which is Durability.

What Is the Durability of Natural Stone?

When we are going to define the durability of a material, it is the term used for an ability of a material to stay for a service life within the surrounding milieu, even without any damage or unforeseen maintenance requirement.

In simple words, natural stone should have resistance to various

  • Weathering actions, including humidity, heat, frost/cold, wind, water, and Sun effects.
  • Chemical attacks, including sewage, corrosion, carbonation, pH, and spills. 

 

What Are Parameters to Measure Durability?

There are numerous parameters, which are coming under consideration when we are going to measure the durability of the natural stones. For instance, according to ASTM (American Society for Testing and Materials) procedures

  • Absorption and specific gravity (C97)
  • Modulus of rupture (C99)
  • Compressive strength (C170)
  • Flexural strength (C880) testing
  • Abrasion resistance (C1353) testing

In practical life, construction industry apply three main metrics, such as

  1. Splitting due to layering impacts.
  2. Crumbling due to orientation and bonding for grains/clasts.
  3. Cracking due to human-oriented breaks and natural fissures.

 

How to Test the Durability of Natural Stones?

Technically, durability assessment of natural stones carried out by taking different approaches, such as

  1. Accelerated Laboratory Durability Tests: freeze-thaw cycling, wetting–drying, and salt crystallization resistance.
  2. Milieu Tests: complex environmental testing in test cabinets.
  3. Exposure site testing.
Accelerated Weathering Exposure

Accelerated Weathering Exposure

Staining

Staining 

Surface Spalling

Surface Spalling

Advanced Surface Spalling

Advanced Surface Spalling

Simulated weathering tests determine the capacity of stones withstanding against climatic adversities like heat/cold, dry/wet, and Sunlight. Acidic rain tests with 4-pH water, flexural strength test with 100-300 temperature cycle, and dynamic module of elasticity tests to evaluate deterioration at periodic intervals.

What Are Durability Specifications for Different Natural Stone Types?

We know general classifications of the natural rocks used in the construction industry is based on the mineral content and composition of the rocks. Siliceous rocks have silica as predominant element while calcareous rocks have calcites.

Due to an abundance of quartz and other silicates, siliceous stones are sturdy and durable whereas calcareous rocks are comparatively soft and useful in somewhat different applications than siliceous rocks. The following data depicts how different types of natural stones are differing in their durability parameters.

The durability of Siliceous Rocks:

Quartzite, Granites, and Sandstone are chief representatives of siliceous types of natural stones.

Durability (Physical property) Testing Results of Quartzite Stone:

Tests Description Results/value
Density Density is the mass per unit volume of a substance. 2.3 to 2.4 Kg/cm3
Loss on Ignition A small quantity of quartzite is heated, thereby letting the volatile substances be released.  Less than 0.5%.
Flexural Strength It is the property of the rock which defines its ability to defy stress 16-40 N/mm2.
Water Absorption The ability of the rock to soak water. As less as 1 – 1.2%.
Hardness It refers to the strength of the rock. 7 units on Moh’s scale.
Compressive Strength It is defined as the load that the rock can withstand without undergoing distortion. 90 to 140 N/mm2.

 

Durability (Physical property) Testing Results of Granite Stone:

Tests Silver Grey Granite Dark Grey Granite Beige Granite JC/T205-92(96) Specifications
Rock Type  Grenodiorite Alteration Diorite  Fin Biotite Granite
Water Absorption (%)  0.28 0.18  0.24 1.00 Max
Density (g/cm3)  2.64 2.78  2.65 2.50 Min
Flexural Strength (MPa)  10.8 24  16 8.0 Min
Compressive Strength (MPa)  174.2 198.2  144.8 60.0 Min
Shore Hardness (HSD)  101 92  100

 

Durability (Physical property) Testing Results of Sandstone:

Tests Results/value
Hardness  6 to 7 on Moh’s Scale 
Density 2.32 to 2.42 Kg/m3
Compressive Strength  365 to 460 Kg/m2
Water Absorption  Not more than 1.0 %
Modulus of Rupture  197-200 Kg/cm2
Porosity  Low to very low

 

The durability of Calcareous Rocks:

Limestone, Marbles, and Travertine are commonly used natural stones in the construction industry.

Durability (Physical property) Testing Results of Limestone:

Tests Results/value
Hardness  3 to 4 on Moh’s Scale 
Density 2.5 to 2.65 Kg/m3
Compressive Strength  1800 to 2100 Kg/m2
Water Absorption  Less than 1%
Modulus of Rupture  197-200 Kg/cm2
Porosity  Quite low

 

Durability (Physical property) Testing Results of Marble:

Tests Results/value
Hardness  3 to 4 on Moh’s Scale 
Density 2.5 to 2.65 Kg/cm3
Compressive Strength  70-140 N/m2
Water Absorption  Less than 0.5% (except Rainforest Green/Brown with 2-3%)
Modulus of Rupture  12-18 N/mm2
Porosity  Quite low

 

Durability (Physical property) Testing Results of Travertine:

Tests Results/value
Hardness  3 to 4 on Moh’s Scale 
Density 2.5 to 2.71 g/cm3
Compressive Strength  80.00 N/mm2
Water Absorption  Less than 0.5%
Modulus of Rupture  12-18 N/mm2
Porosity  Quite low

 

Conclusion:

We have seen how calcareous stones are differing from the siliceous stones in hardness, density, water absorption, porosity, and modules of rupture like parameters. Therefore, stone experts in the industry prefer predominant use of calcareous stones in interior applications while siliceous for exterior applications.

Granite and quartzite are the best options for kitchen countertops and similar applications in the interior spaces while Travertine stone is the number one choice for swimming pool deck and patio like exterior applications.

If you are interested in the creation of a durable building using natural stones, World of Stones, Maryland, USA, is an ideal destination to obtain durable natural stones for your next projects. Moreover, you can get perfect guidance in due course. Please visit our website and come in contact with our stone consultants.

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