Is Limestone Permeable? (ANSWERED)

Yes, limestone is generally permeable, though it depends upon the composition of the particular limestone.

Limestone rock is a versatile and important commodity.

Much of its value comes from its permeability and its light weight.

But what does this even mean? Why does permeability matter?

To answer these questions, it’s important to discuss what limestone is.

This will help explain the benefits that being permeable give it.

Is Limestone Permeable? (EXPLAINED)

What is Limestone?

Limestone’s definition is tricky.

The technical description refers to any rock that’s at least 50% calcium carbonate.

The rest features some other type of material.

Most limestone forms when coral fragments are pressed together for millions of years.

This leaves a lot of variables about limestone types, of which there are several.

Each one gets its name based on its composition and how it’s formed.

What it looks like and other physical properties matter here as well.

This determines its potential uses. Some common types of limestone are:

Chalk: It’s created from the accumulation of microscopic marine organisms and algae.

It also crumbles easily and has a light gray or white coloring. In the past, this was a type of material used to write on blackboards.

Coquina: It’s usually found on beaches.

Gastropod, mollusk, trilobite, coral, or other invertebrate remains form this type of limestone.

Crystalline limestone: It’s formed when limestone faces chemical activity, pressure, and heat.

This transforms the calcite in the rock.

When the calcite crystals are big enough, the naked eye recognizes it as marble.

Dolomitic Limestone: It’s formed when calcium carbonate and magnesium-rich groundwater interact.

The magnesium changes the calcite into dolomites.

Lithographic limestone: This is a dense type of limestone with a very fine and uniform grain size.

The name seems familiar because of its past.

They used these stones in an old printing process called lithography.

This printing style produced many of the finest posters and navigation maps of its time.

Oolitic limestone: With this type of limestone, calcium carbonate wraps around a nucleus.

Over times, it creates layers like those of an onion.

The nucleus is usually coral or shell fragments, sand grains, or fecal debris.

What Does Permeable Mean?

Permeable refers to the degree limestone let gasses or liquids pass through them.

Limestone is also porous.

This refers to its ability to hold liquids.

Limestone has a lot of faults, joints, and bedding planes that allow water to move through it quickly.

Different limestones don’t have the same permeability and porosity.

Some have no permeability and huge porosity.

Others have poor porosity and good permeability.

It depends on the rock’s structure.

Is Limestone Hard?

Limestone is a hard, compressed rock formed over millions of years.

But, compared to others, it’s a soft stone.

It won’t dissolve in water, but acidic liquids are different.

When contact with vinegar or other acids occurs, weird things happen.

The limestone bubbles, deteriorates, and then neutralizes the acid.

Why Does Permeability Matter?

Permeability is important because of its usefulness in controlling water flow.

Let’s take limestone pavements, for example.

These permeable pavements are great at reducing runoff volume.

The type of limestone used in this type of construction has high permeability and porosity.

This lets it absorb rain into the ground and away from storm drains at a rate of 3-5 gallons a minute.

That’s for every square foot of surface area.

This rate far exceeds what’s needed to prevent runoff during most rainstorms.

What Other Uses Does Limestone Have?

Limestone is a great substitute for hard silicate rocks.

It’s more abundant and easier to mine. It’s also softer, cheaper, and doesn’t cause the same amount of wear and tear on line equipment.

Crushed limestone has a variety of uses as landscaping and construction material. Some of these uses include:

Asphalt pavement

Structural fill

Road base

Railroad ballast

Limestone also creates:

Dimension Stone: It’s limestone that’s cut into slabs and blocks of certain dimensions.

It’s used for floor tiles, stairway treads, window sills, and many other uses.

Roofing granules: Manufacturers crush this limestone to a very fine particle size.

Roofers use it as a heat and weather resistant coating on asphalt shingles.

They also use it on other types of roofing material.

Lime: Calcium carbonate that’s heated to a very high temperature in a kiln produces a gas and a solid.

The gas is carbon dioxide gas and the residual product is calcium oxide.

The agricultural and chemical industries use calcium oxide a lot.

Its powerful acid neutralization properties are a boon.

Animal feed filler: Calcium helps chickens create strong eggshells.

When their natural intake isn’t enough, farmers must find a substitute.

This is usually in the form of calcium carbonate as a dietary supplement.

They also give it to dairy cattle because these animals lose a lot of calcium in the milking process.

Are There Any Negatives To Using Limestone?

Limestone is versatile and has several varieties of uses.

But it has its weaknesses as well. Intense weather (like heavy rain) has a degrading effect on limestone.

Both its appearance and structural soundness are compromised.

The good news is, it takes at least two of these factors to cause real damage.

Acid rain is a great example. The mixture of rainwater and atmospheric gasses dissolves limestone.

The Bottom Line

Limestone’s standard permeability and porosity makes it a strong but soft rock. 

This might be a disadvantage to some, but they’re forgetting one important thing.

These properties also give limestone a versatility not easily matched in the construction or agricultural industries. 

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