The Splendor of Sand

Sand in your eyes causes pain, but how soothing it is under your toes! Vast amounts of it are suspended in seawater, but it also abounds in bone-dry deserts. Hordes of creatures flee its encroachment, but for others, it is home. It is often considered a nuisance, but without it, modern living would be nearly impossible.

From the above description, sand seems to be somewhat of a paradox. Just what is sand, and where does it come from?

A Rough Beginning

Sand is composed of particles of minerals, rock, or soil, with quartz being the most common constituent. Peaks that once stood rock solid have eroded into sand. How does such erosion occur?

Sand is often the product of ocean violence. Waves smash against coastal cliffs, and these collisions loosen and rip away slabs of rock. Very large pieces surrender before the unremitting assault, being sloughed off in chunks into the surf. The churning sea grinds off sharp edges, producing boulders. Constant motion gradually wears them into pebbles, and these are crushed into still smaller particles, which we know as sand. Sometimes the sea carries the sand off, but in many places, waves heave the sand back ashore, leaving pristine beaches.

When cold weather combines with ocean violence, frozen water becomes trapped in rock, producing icy wedges that split the stones. The fracturing goes on, reducing large rock masses to smaller and smaller pieces, which eventually become sand.

The wind too plays a role, lifting grains of sand and driving them against rock masses. The abrasion creates more sand. Layers of rock hundreds of feet thick give way before this natural form of sandblasting. Meanwhile, the wind scatters the resulting sand, stretching it out like a carpet on the desert floor.

Over millenniums, these harsh processes have yielded countless tons of sand. Many people would be delighted if it were used only to provide contoured cushions at the beach. But sand's value reaches far beyond the shore, as we shall see.

Tiny Grains, Huge Benefits

To a large degree, our eating and drinking is dependent on sand. How is that? In one way or another, all our food comes from the vegetation of the earth. Sand and its finely ground cousins silt and clay supply minerals that plants need. Also, sand in the soil allows air and water to circulate. Thus, plant roots can easily absorb nutrients. But how is sand involved in quenching our thirst?

If you fill a one-quart (one-liter) jar with dry sand, you can add a third of a quart (300 milliliters) of water to that same jar without making it overflow. This is so because sand is porous-that is, between its grains there is a lot of space. In fact, there are sand "water jars" large enough to supply large cities with the life-giving fluid. What are they?

Geological formations called aquifers lie below much of the earth's surface. Composed of vast layers of sand and other porous minerals, these contain water that has been filtering downward for possibly thousands of years. Scientists calculate that these unseen "water jars" hold 40 times more fresh water than all the lakes and rivers on earth. Wells tap aquifers for their precious liquid, which sustains the lives of millions.

Sand Before Your Eyes

You may be walking on sand every day without ever going to the beach. Are streets or sidewalks in your hometown paved with concrete? In some cases, sand makes up one quarter of this common building material. Hundreds of millions of tons of sand are consumed annually as construction material, so much so that some places have experienced shortages of sand.

While sand generally lies underfoot, in another form it may be right before your eyes. The screen on your computer is likely made from sand, as are the lenses of mountaintop telescopes and desktop microscopes. The same is true of crystal vases and your bathroom mirror. Those items are all made of glass, and sand constitutes over half the raw material that is used in glassmaking. How is sand used to make glass?

Sand and other ingredients are mixed and then melted at temperatures exceeding 2,600 degrees Fahrenheit (1,400°C). The resulting viscous liquid can be rolled, blown, bent, drawn, and spun into almost any form. Glass fibers are even woven into cloth. But whether it promotes beauty or industry, whether it refracts or reflects, smooth, clear glass comes from the opaque grit of sand.

Sand on the Move

Imagine a hill 250 feet high that moves. This happens when piles of sand called dunes migrate, pushed by the wind. In some parts of the Sahara, dunes seem to string out their undulating ridges endlessly.

When humans establish themselves nearby, dunes may pay them an unpleasant visit. Indeed, sand on the move has been known to block highways, swallow houses, and bury entire towns.

Abounding With Life

As lifeless as sand may appear, many creatures call it home. Foxes, snakes, and scorpions burrow in desert sand during the day. Sleeping through the heat, they come out at night to hunt for food. Along Namibia's Skeleton Coast, in southwest Africa, elephants roam the vast dunes. They seem to have fun on the steep, sandy inclines, sliding down dragging their back legs. The "ship of the desert," also known as the camel, cruises the sand seas of Asia and Africa.

Some animals come up out of the ocean to make use of sand. When their biological clocks sound the alarm, horseshoe crabs, sea turtles, and small fish called grunions ride the surf to the shore. There they lay their eggs to incubate in the softness of the sand.

For certain flowers, a dune is as comfortable as a window box. Sea rockets, beach peas, and beach morning glories flourish in sand and push their heads back up even when a dune buries them. Their long roots pull up water and nutrients to feed dainty blossoms-dabs of color on the monotone canvas of sand.

Frankie Goh is a full-time family counselor. He manage and host a website : Earn Money Online http://www.ezy-cash.com
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Various Uses of Limestone

Limestone is very popular and renowned in architecture, and has many samples around the world, particularly in North America and Europe, is made primarily of this material. So many manufactured buildings in Kingston, Ontario, Canada were manufactured from limestone, and it was named as Limestone City. Limestone is readily obtainable and comparatively easy to cut into blocks or more complicated carving. It is as well long-lasting and stands up well to any exposure.
Limestone is further used as a frontage on some of the skyscrapers, in way of thin plates for covering rather than solid blocks. In the United States, Indiana, and most remarkably the Bloomington area, has long been a source of high-class quarried limestone recognized as Indiana limestone. Many well-known buildings in London are created from Portland limestone.
Pure limestone could be more or less white in color. Due to its impurities, such as clay, organic remains, sand, and few other materials, much novel limestone’s come in various colors, particularly on weathered surfaces. Limestone might be crystalline, clastic, granular, or huge; all in fact depends on the system of formation. Folk and Dunham classifications are described more precisely when it comes to limestone.
Other uses include:
• He is a producer of quicklime and slaked lime. • Used for cement and mortar. • Pulverized limestone is used as a soil conditioner to offset acid soil conditions. • Crushed for use as collective - the solid base for many roads. • Geological arrangements of limestone are amid the best petroleum reservoirs • For glass making• Limestone is quarried for roadbeds; building and other landscape building, and cement manufacture.
As limestone is valuable natural resources, it is used to make things that we all require, such as concrete and glasses. Limestone was as well admired for building block in the middle ages. Many medieval churches and few other castles in Europe were created by limestone. Beer stone was also well-accepted form of limestone that were used for medieval buildings in Southern England.

Uma is a copywriter of http://www.cangelosi.com/Limestone_Formation.html She had written various articles in different topics on Granite countertops. Contact her at cangelosi2@gmail.com
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Concrete - How Concrete is Made and the History of Concrete

Concrete is the most widely used manmade product in the world. It powers a $35 billion industry, one of the largest on Earth. Concrete is used to make a variety of structures a which you use everyday.

Concrete is a construction material that consists of, in its most common form, cement, gravel and sand, and water. Concrete is the most highly used manmade product on Earth. It is used to make pavements, building structures, foundations, motorways/roads, overpasses, parking structures, brick/block walls and footings for gates, fences and poles. Approximately six billion cubic metres of concrete are produced every year, which is one cubic metre per person on Earth! Concrete commands a $35 billion worldwide industry and employs, in the United States alone, 2 million people.

The origins of concrete can be traced back to the Babylonians, who used a clay-mix similar to concrete. However, the modern-day form of concrete was not invented till 1756, when British engineer John Smeaton pioneered the use of cement in concrete. His ingredients included pebbles and powdered brick as aggregate. Nowadays, recycled materials are becoming increasingly more popular as ingredients in concrete due to higher public awareness about ecological sustainability and environmental damage.

The composition of concrete is traditionally relatively simple. However, modern concrete is often a complicated mix, ensuring durability and longevity. Cement is the main ingredient in concrete. Portland cement is the most common cement in circulation, which is just a basic mix of mortar and plaster.

Water is another ingredient in the manufacture of concrete. The w/c ratio (mass ratio of water to cement) is the key factor that determines the strength of Concrete. A lower w/c ratio will yield a concrete which is stronger, while a higher w/c ratio yields a concrete with a lower strength. Water also affects the workability and consistency of a concrete.This water and cement paste hardens over time, and both fine and coarse aggregates are added to provide bulk. Widely used aggregates include sand, gravel and crushed stone. Decorative stones such as, small river stones or crushed glass are sometimes added to the surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers.

Ad mixtures are also added to a concrete mix to give it certain characteristics not obtainable by basic production. Admixtures come in powder or paste form and generally consist of no more than 5% of the entire mixture.Concrete has many characteristics including:

Workability – ability to mould to certain shapes
Curing – keeping concrete under certain conditions till it hydrates
Strength – high compressive strength, low tensile strength
Elasticity – relatively low
Expansion and shrinkage – provisions must be made for both
Cracking – abnormal drying rate will result in cracks
Creep – the permanent movement of a slab of concrete

Concrete is used for many structures. Mass concrete structures are structures built with one, giant concrete slab so that there are no weak points, such as dams or shelters. Reinforced concrete structures have bars of steel running through the concrete to ensure strength and stability. Pre stressed concrete structures have a predetermined stress level which will never be exceeded, as they will only carry their own weight. Concrete is an amazingly versatile material. Whether you are building some of the largest structures in the world or a small pathway, the evolution and discovery of concrete has changed our world

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