When we talk about limestone and everything about it, then it may be a vast subject to cover all perspectives like pure science and applied science. Therefore, I would like to restrict up to applied aspects only in the current post.
Sedimentation – A Process of Rock Formation
For millions of years, a sedimentation process is going on the surfaces of the planet earth. In sedimentation, one layer of organic, non-organic, and other substances laid on another in stacks. The buried layers getting compressed due to increased weights of top layers.
So, the process is known as Diagenesis that turns sediment to rock. During diagenesis, water squeezes out of the pore spaces and forms Grains in the mass of the rock — the size of grains ranging from 0.001mm to 0.00004 inches. When grain formation takes place due to fossils, the size of fossils determines the shapes, patterns, and orientation of the grains.
Decomposition, formation, deformation, and myriads of various activities are taking place beneath the soils and sea waters. Sedimentation also has yielded different types of sedimentary rocks, and limestone is consisting of a big portion of those rocks.
What Is Limestone at Different People’s Perspective?
Now, we got what sedimentation and sedimentary rocks are. Limestone is a type of sedimentary rock containing 10% of all rocks. Limestone is chiefly containing calcium in various chemical formats including calcium carbonate (CaCO3) and known as Calcite in the geological term.
However, common people hardly familiar with professional terminology so it is better to simplify it. Chalk is highly familiar substance and used a lot in day-to-day life.
- Chalk sticks used by teachers.
- Chalk powder & crushed stones used by contractors and Mason in the construction industry, chemical industry, and elsewhere.
- Seashells and crushed limestone particles are part of animal feed today.
- Whole stones like marbles and travertine are considering natural beauty adding components in the construction industry.
These all are common examples of limestone usages and can give an idea about what we are talking about.
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How Limestone Defined?
Geologists and other professionals define limestone as a rock, which has at least 50% calcium carbonate by weight and famously known as Calcite.
What Is the Constitution of Limestone?
Apart from calcites, limestone also contains other minerals and forms small particles found in quartz, feldspar, pyrite, siderite, and clay minerals — large nodules in Chert (chalcedony, Flint, Jasper), pyrite, and siderite.
How Is Limestone Formed
At geological perspective, the formation of limestone takes place in two different environments, sedimentation in deep marine water and by water evaporation during cave formation.
Marine Environment to Form Limestone
In oceans, a variety of living organism thriving in the ecosystem. Diatoms like the tiniest creatures to Whale like giant fishes are adding their Fossils (skeletal debris) during the sedimentation process. The fossils of animals chiefly contain calcium as mineral composition.
The skeletons of animals also leave imprints within the mass of rocks and add decomposed calcium in the rock to form (Lithographic) limestone.
The limestone like ooids, peloids, intraclasts, and extraclasts are composing carbonate grains.
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Limestone Forms by Water Evaporating Environment
Supersaturated meteoric water with calcium and other minerals is often streaming out or forming caves. Due to the evaporation of water, the precipitation of minerals along with other substances takes place. It forms Spikes in Caves.
The cave spikes formation process mostly happens either on the ceiling (Stalactites) or floor (Stalagmite) of the caves, and leave icicle-shaped calcites behind.
Travertine is forming through an evaporation process and missing fossils injected grains at all. Another stone type is “Tufa” forming by hot springs and shores of lakes.
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Where Is Limestone Found
The shallow water areas in the Caribbean Sea, Indian Ocean, Persian Gulf, Gulf of Mexico, around Pacific Ocean islands, and within the Indonesian archipelago are rich in limestone depositions.
Limestone formation requires abundant of Corals. Algae, Mollusca, fishes, diatoms, and other calcium-rich fauna in the water, be it marine or land water. Meteoric water spring areas also are the best places to get non-grained limestone resources.
The occurrence of limestone takes place in different depth or strata of the earth, and based on it; they are classified:
- Shallow Water (Stagnant) Deposits – in Lakes
- Deep-sea Deposits – in Seas
- Freshwater (Streaming) Deposits – in Springs/Rivers/Underground Water
- Eolian (Wind-based) Deposits
- Evaporative (Vapor-based) Deposits – in Meteoric Caves
Known Varieties of Limestone
In stone quarrying and manufacturing industry, limestone is known as different names and used for various purposes. Let’s check the most common names here.
Chalk:
- It is soft, so crack & break easily up to powder form
- Fine-grained and textured stones
- White to light grey in colors
- Presence of fossils, shells, and microscopic fauna becomes apparent in many stones when quarried
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As its name suggests, it consists mainly of fossils in the micro to macro sizes.
Brachiopods, gastropods, crinoid stems, and hard-shelled Mollusca are found in macroscopic fossiliferous stones.
Diatoms, single-celled, and two layered multiple celled organisms are found in microscopic fossiliferous stones.
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Lithographic Limestone:
- It is dense in structure, so hard in nature
- It fine-grained and homogenous rock, mostly yellowish in color
- Defect-free and smooth texture offer surfaces to use in lithographic in the early days of printing industry evolution.
- You can cut in thin slices and used as a lithographic plate
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Oolitic Limestone:
Oolite means egg-shaped, so such limestone containing spherical granules imitating small eggs and ranging between 0.25 to 2.0mm.
It is excellent material for decorative and other limestone usages in construction & non-construction industries.
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Coquina:
It is poorly consolidated stone composed of whole fragments of Mollusca shells. So, it contains the macroscopic size of particles sorted by natural forces like water and wind waves. It is an ideal material for landscaping and home decoration.
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Travertine:
As discussed earlier, travertine is non-biologically/Chemical formation through the evaporative process takes place in the roof of caves known as Stalactites, on cave floors as Stalagmites, and during flow as Flowstone.
Travertine looks extremely beautiful when selected in different colors and polished well.
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Tufa:
It is a combination of the biological and chemical process takes place near waterfall like areas. Unlike travertine, it is found in cold spring areas and offer porous and softer stones than travertine used in various architectural applications.
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Today, with some significant applications, none care the products in the market. However, limestone has multiple applications. Let’s see some general and some particular to the construction industry.
Uses of Limestone in General
Limestone- as the raw material in the manufacturing of
- Quicklime – Calcium oxide
- Slacked lime – Calcium hydroxide
- Portland Cement – Used limestone along with shale, sand, and other materials in heated Kiln as hardening material when mixed with water
- Mortar
Agricultural – Calcium components in calcites of limestone can neutralize acidic soil gradually. Therefore, pulverized limestone is the best choice as a soil conditioner and used as Gypsum in bulk.
Aggregates – Crushed limestone used to apply in the soil base for roads, paths, and driveways, and other external applications.
Reagent – It reacts with sulfur dioxide and leads to desulfurization of fuel gas emissions and other pollutants in the air.
Glass Making – It has a certain use in glass making processes.
Smelting & Refining: During iron and other metal heat smelting & refining processes, limestone reacts with impurities in raw materials and remove it once the slag forms out of those processes.
Pharmacy and Healthcare – Most of pills and tablets are made of chalk and calcium powders. Toothpaste and similar oral gels, and beauty creams demand calcium powder and chemicals, which are mainly come from limestone of different grades.
Animal Feed: Livestock like poultry and productive mammals need calcium as chief components in their feed and limestone is a commercially viable solution instead of bones.
Plaster of Paris: POP is famous in the construction of modern temporary sculptures, ceilings, and used in orthopedic applications. POP is based on calcium minerals and uses limestone heavily.
Filter: limestone aggregates and crushed particles of different sizes are the best material to create sewage and other filtering applications, as lime has great neutralizing capacities to save from many hazardous chemicals and dust.
Uses of Limestone in the Construction Industry for Exterior Applications
Limestone is a versatile material in the construction industry. When limestone applied to the exterior of the building, it improves the aesthetics of the overall building and increases the total value of the property.
Limestone is available in almost all regions of the world thanks to its abundance. For commercial/professional applications in the construction industry, limestone enjoys a high favor due to it’s easy to cut properties. Among users, the easy to clean and to maintain attributes of limestone establishes it as a prime choice.
Limestone is a bit softer material against other siliceous rocks. You can cut big size cubes to thin tiles or veneer using modern stone cutting tools and techniques.
The next thing is durability/longevity and strength of limestone, which render it an excellent choice for a variety of exterior applications. For instance,
Limestone as Dimension Stones:
We know limestone can be cut into pieces of any dimension. Whole stones or cubes also prove better structural material and gives the property a classic look.
Taj Mahal in India is a historical structure entirely made from marbles, and similar limestone gathered from across the world.
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Limestone as Stone Veneer:
Exterior wall cladding is possible with limestone veneer. It can help you decorate your entire exterior facing walls, entrance, and backyard.
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Limestone as Roofing Granules:
Crushed limestone with different sizes and colors, when mixed with cement and sand, can act as a top coat on RCC roofs/slabs and provide a heat-resistant coating. Roofing granules from crushed limestone also cover the asphalt-impregnated shingles and roofing.
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Limestone in Drainage Ditches:
Exterior home landscapes or gardens often need drainage ditch building to save heavy runoff during rainy days. Crushed limestone and stepping stones can save runoff as well as provide a path to pass safely during wet seasons.
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Limestone in Swimming Pool:
Travertine is an excellent material for swimming pool construction. It is an excellent choice for coping and pool deck area building due to non-slip, heat-resistant, and toughness property attributes.
Limestone proves the affordable and cool-looking choice when travertine or some variety of marbles used in pools.
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Siding, Sills, & Water Table with Limestone:
Limestone used for centuries in the construction of door/window sills, headers, and water tables to protect the building as well as garner its natural beauty.
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Limestone in Garden:
The modern gardens have enough room to incorporate natural stones in various components and limestone is an excellent choice.
Garden periphery walls, benches, tables, and side walls in limestone are not new things and look aesthetically beautiful.
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