Why is there stones

The non-trivial movement caused by heat expansion and contraction along the length of the rail would cause it to break or buckle if any of it were fixed in place. So instead, the rails are attached to the sleepers by clips or anchors, which hold them down but allow them to move longitudinally as they expand or contract. So there you have it: a centuries-old process that is extremely effective at facilitating the movement of people and material over thousands of miles The ballast distributes the load of the ties which, in turn, bear the load of the train on the track, held by clips across the foundation, allows for ground movement, thermal expansion and weight variance, allows rain and snow to drain through the track, and inhibit the growth of weeds and vegetation that would quickly take over the track.

This post originally appeared on Quora. Click here to view. BY Quora. Big Questions trains transportation travel. Subscribe to our Newsletter! It would seem that you could just nail them or bolt them down to the ties, but that won't work. The non-trivial movement caused by heat expansion and contraction along the length of the rail would cause it to break or buckle if any of it were fixed in place.

So, instead, the rails are attached to the sleepers by clips or anchors, which hold them down but allow them to move longitudinally as they expand or contract.

So there you have it: a centuries-old process that is extremely effective at facilitating the movement of people and material over thousands of miles The ballast distributes the load of the ties which in turn bear the load of the train on the track, held by clips across the foundation, allows for ground movement, thermal expansion and weight variance, allows rain and snow to drain through the track, and inhibits the growth of weeds and vegetation that would quickly take over the track.

David S Rose , entrepreneur, investor, mentor. Why are there crushed stones alongside railway tracks? Ask a question, get a great answer. Learn from experts and get insider knowledge. This is especially true when it comes to one of the basic building materials in ready mix concrete, asphalt, masonry, and hardscaping: types of stone. We all know a stone when we see one, and we know they are important in construction, but what specific roles do they play in different construction projects?

In this article, we are going to take a deep dive into the types of crushed stone and gravel, how they are made, and their basic applications.

You may not be a quarry expert at the end, but you will understand the basics for your next concrete or hardscaping project! Are you ready to learn more about gravel and crushed stone? Most crushed stone is produced in quarries and is crushed when machinery breaks up and crushes larger rocks.

Instead of being shaped or formed naturally, such as in a riverbed or canyon, crushed stone is produced with man-made machinery and processes. So what is the process in creating crushed stone? It begins with using a rock crusher in a quarry or site with plenty of large rocks. There are many types of crushers, but their main job is the same: Crush larger rocks into smaller pieces to be used for construction material. Crushed stone is then passed through different screeners to be organized and stored in different piles according to their size.

The screening process starts by removing larger stones, then medium stones, and eventually goes all the way down to the stone dust. This screening is important because contractors need very specific types of crushed stone to complete different types of projects. After being sorted into different piles depending on the size of the stone, the stone is ready to be shipped from the quarry.

Quarries deliver directly to job sites, to concrete plants, or to wholesale distributors who sell the stone through retail to customers. You can even purchase bags of stone, whether it is for construction or decoration, from Lowes and Home Depot.

So has crushed stone always been used widely for construction? The simple answer is no. In fact, crushed stone did not become a staple in construction until after WW2 for a simple reason: The equipment did not exist to crush or move stone efficiently.

Because large stones and quarries are hard on tires and require heavy metal, crushed stone was hard to make and transport until heavy machinery with tracks was developed.

WW2 expedited the development of this machinery, and crushed stone began to be widely used in construction projects in the s and s. Large-scale building projects, particularly in infrastructure like the Eisenhower Interstate System , helped usher in an era where crushed stone was used in almost every part of construction.

Foundations, concrete, drainage systems, and roads were all needing large quantities of crushed stone. What are the concerns with the wide-spread use of crushed stone? Because crushed stone mostly comes from quarries, there has been growing geological and environmental concern over the large number of quarries operating and their long-term effects. In response to this, construction companies are beginning to use recycled construction products to replace crushed stone.

An example of this often occurs when a road is being replaced or resurfaced. Many road construction companies are beginning to grind and crush the existing road as they remove it. This crushed road, which is essentially crushed stone, then becomes the base for the new road.

How much recycling is done? The exact amount of crushed stone recycling is unknown due to a lack of reporting. Much of the crushed stone is also recycled right on the construction site, especially with road construction, and this makes it difficult to measure. The most common use for recycled crushed stone is as a base for roadways, especially when the old road can be torn up, crushed, and reused. Concrete blocks and bricks can also be crushed and recycled as a base.

Gravel is similar to crushed stone because it is a type of rock, but gravel is produced naturally. One of the key differences in the look and feel of crushed stone and gravel is the edges of the stone. Crushed stone often has an angular and jagged edge that occurs during the crushing process. Gravel, on the other hand, typically has a very smooth texture and surface because of the natural weathering and wear of being exposed to the effects of running water.

Unlike crushed stone, gravel is usually sold and used in its natural state. If it is crushed, gravel loses its unique smooth rounded texture and becomes crushed stone. To provide clarity and avoid confusion, we will stay with the definition that gravel cannot refer to crushed stone and must remain in a natural state. Also, when talking about natural rock and stone, it is important to know if they are igneous, sedimentary, or metamorphic. Igneous : Igneous rocks are formed after molten rock or lava solidifies.

Sedimentary : Sedimentary rocks are formed over time by the accumulation of small particles becoming cemented together. This piecing together of the rock often produces layers in the rock.