A variety of physical and mechanical properties must be measured and must comply with standards set by the American Society of Testing and Materials ASTM. These properties include physical dimensions, density, and mechanical strength. Another important property is freeze-thaw durability, where the brick is tested under conditions that are supposed to simulate what is encountered in the outdoors. However, current tests are inadequate and do not really correlate to actual conditions.
What passes in the laboratory may not pass in the field. Therefore, the brick industry is trying to develop a more accurate test. A similar problem exists with a condition known as efflorescence, which occurs when water dissolves certain elements salt is among the most common in exterior sources, mortar, or the brick itself.
The residual deposits of soluble material produce surface discoloration that can be worsened by improper cleaning. When salt deposits become insoluble, the efflorescence worsens, requiring extensive cleaning. Though a brick may pass the laboratory test, it could fail in the field due to improper design or building practices.
Therefore, brick companies are developing their own in-house testing procedures, and research is continuing to develop a more reliable standard test. Currently, the use of brick has remained steady, at around seven to nine billion a year, down from the 15 billion used annually during the early s. In an effort to increase demand, the brick industry continues to explore alternative markets and to improve quality and productivity. Fuel efficiency has also improved, and by the year brick manufacturers may even be firing their brick with solar energy.
However, such changes in technology will occur only if there is still a demand for brick. Even if this demand continues, the brick industry both here and abroad faces another challenge: it will soon be forced to comply with environmental regulations, especially in the area of fluorine emissions.
Fluorine, a byproduct of the brickmaking process, is a highly reactive element that is dangerous to humans. Long-term exposure can cause kidney and liver damage, digestive problems, and changes in teeth and bones, and the Environmental Protection Agency EPA has consequently established maximum exposure limits.
To lessen the dangers posed by fluorine emissions, brickworks can install scrubbers, but they are expensive. While some plants have already installed such systems, the U.
If the brick industry cannot persuade federal regulators to lower their requirements, it is quite possible that the industry could shrink in size, as some companies cannot afford to comply and will go out of business. Bender, Willi and Frank Handle. Brick and Tile Making. Bauverlag GmbH, Jones, J.
Ceramics: Industrial Processing and Testing. Iowa State University Press, Robinson, Gilbert C. Ceramics and Glasses. ASM International, , pp. Hall, Alvin. Richards, Robert W. May, , pp. Sheppard, Laurel M. September, , pp. Toggle navigation. Made How Volume 1 Brick Brick.
To produce brick, the raw materials are first crushed and ground in a jaw crusher. Automatic chamber dryers are also in wide use. Bricks sit on extruded bars and are placed in rows where they are dried in the heavily regulated climate. Generally, bricks will stay on the same cars used for the drying process to take them into the kiln.
This is where firing takes place. Kilns have evolved significantly over the years, increasing capacity, consistency and economic efficiency. Most kilns in operation are tunnel kilns, whereby bricks are pushed through a long, specially built tunnel, whilst being fired.
They used to be high and narrow. Now they're generally lower and wider, allowing more bricks to be fired at once. Most bricks these days are gas fired in order to better regulate a continuous temperature. But in some cases, a coal fire may be used. They are removed or 'dehacked' from the cars and then 'set' in stacks where they can then be wrapped and packaged for distribution. If you hadn't realised, we love bricks.
And we love finding out where they come from. We hope you found this interesting too. If this has got you in the mood for some brick browsing before Christmas, then check out our brick library section. Brick Library. How Are Bricks Made? Millions of bricks are manufactured each year all over the world. But have you ever stopped to wonder how they get made? In this post, we'll be going through how a typical kiln-fired brick is made. Raw Materials The main ingredient of most bricks is clay.
It always has been. What else is in a brick? The final crucial ingredient in the brick making process is water. The Manufacturing Process We now come to the manufacturing process itself. Forming Bricks There are a number of different options for this stage that are used around the world today. The ancient Persians and Assyrians made stronger bricks by roasting them in kilns. This is much hotter than the mild roasting or calcination used to make top dressing for baseball fields.
The Romans advanced the technology, as they did with concrete and metallurgy, and spread fired brick to every part of their empire. Brickmaking has been basically the same ever since. Until the 19th century, every locality with a clay deposit built its own brickworks because transport was so expensive.
With the rise of chemistry and the Industrial Revolution, bricks joined steel , glass and concrete as sophisticated building materials.
Today brick is made in many formulations and colors for a variety of demanding structural and cosmetic applications. Over the period of firing, brick clay becomes a metamorphic rock. Clay minerals break down, release chemically bound water, and change into a mixture of two minerals, quartz and mullite.
The quartz crystallizes very little in that time, remaining in a glassy state. It is named for its occurrence on the Isle of Mull in Scotland. Not only is mullite hard and tough, but it also grows in long, thin crystals that function like the straw in adobe, binding the mix in an interlocking grip.
Iron is a lesser ingredient that oxidizes into hematite, accounting for the red color of most bricks. Other elements including sodium, calcium and potassium help the silica melt more easily—that is, they act as a flux. All of these are natural parts of many clay deposits. Earth is full of surprises—consider the natural nuclear reactors that once existed in Africa—but could it naturally produce true brick? There are two kinds of contact metamorphism to consider.
First, what if very hot magma or erupted lava engulfed a body of dried clay in a way that allows the moisture to escape? I would give three reasons that rule this out:. But the Earth's interior has not reached that temperature since the Early Proterozoic Era more than 2 billion years ago.
And at that time there was no oxygen in the air, making the chemistry even more unlikely. On the Isle of Mull, mullite appears in mudstones that have been baked in lava flows. It also has been found in pseudotachylites , where friction on faults heats dry rock to melting. These are probably a far cry from real brick, but you should go there yourself to make sure.
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