Brick Manufacturing

Page history last edited by Sarah Kelley 3 years, 2 months ago

Overview

This page is for students working on the Brick Manufacturing video podcast. It will have the following features:

Student notes from their individual research, edited into a draft script
Revisions by team members and the Subject Matter Expert
Questions to ask the SME and others during the interviews at the sites
Transcripts of video clips of the interviews and tours
Final approval by the SME and company PR people

Team

Zac Watson: History and types of bricks
Jonny Fay: Processes for brick manufacturing
Sarah Kelley: Raw materials for bricks, environmental impact of bricks
Megan Johnston: Coloring and building with bricks

Timeline

Initial Research: November, 2008
Detailed Research/Draft of Script: Dec. 15-16, 2008
Contact with SME: By Dec. 19, 2009
Tour of Companies (Videotaping): Jan. 7-9, 2009
Capture and Transcription/B-Roll Creation: Jan. 20-23, 2009
Final Script Complete with Approval of SME: Jan. 23, 2009
Video Editing - Draft: Jan. 26-30, 2009
Alpha Testing/Revisions: Feb. 2-6, 2009
Beta Test/SME Checkoff: Feb. 9-13, 2009
Export to Podcast/Add Metadata: Feb. 17-20
Post to Blog, Upload to iTunes: Monday, Feb. 23

Script Sections:

Lead In:

What is a brick? What are the different types of bricks? Why have they been used for thousands of years? Bricks are most commonly used for building and pavement. In the United States brick pavement wasn’t able to withstand heavy traffic. But, lately bricks have been coming back as pavement to slow traffic in certain areas and for pedestrian use in sidewalks.

History of Bricks:

Some of the oldest shaped bricks go back as far as 7500 BC. Most bricks of that age are found in the areas around the upper Tigris River in Turkey. The first bricks were sun-dried bricks which were not very durable or long lasting. It was not until

around 3000 BC that kiln-fired bricks were invented in the Middle East. They were much more resistant to cracking by cold weather and lasted much longer in general. Bricks were used as a building material because they have the added benefit of

keeping the warmth of the sun in them and releasing it at night. Bricks are very easy to use because of their uniform shape and consistency of form.

Brick Laying:

The strength of the structure being built and also the finished look depends greatly upon how the bricks are layed or placed into their final place. Depending on what you're building you could need a more complicated pattern to ensure stability.

Mortar:

Mortar is a combination of powdered cement, sand, and water. Depending on what you are building there are three types of mortar you could use. Type N mortar is often used in Non-load bearing projects such as BBQ grills and chimneys. Type S mortar is a high strength mixture that is used in foundations, retaining walls and, driveways. Type M mortar is a very high strength mixture for load bearing stone walls. The difference in strength comes from the amount of cement in the

mixture.

Types of Bricks:

Mud Bricks

Mud bricks are made with mostly clay with about 25-30% sand or else it shrinks quite a bit in the firing process. The clay is ground with water until it reaches the right consistency. The clay is then put into steel moulds and dropped into a kiln to be fired at 900-1000 degrees.

Bulls Trench Kiln

In Pakistan and India most brick work is done by hand and uses the Bulls Trench Kiln technique to make energy efficient bricks. The bricks are made much the same as a normal mud brick but the firing is an extremely different process. The firing is

done in a large hole dug in the earth about 2 to 3 meters deep. In the center is built a small chimney with a kiln beneath it. Around the edges of this chimney the bricks are placed. The hole is covered with plywood and fuel is fed in through the chimney. A small opening is let in for air to flow through and the air is heated by the bricks and

exits out the chimney creating suction.

Fly Ash Brick

In the year 2007, Henry Liu, created a new type of brick using fly ash and water and compressed it for 2 weeks at 4000 psi. This new brick has a high concentration of calcium oxide and is considered “Self Cementing.” The brick is toughened using a

chemical during its compression that inserts tiny air bubbles in the brick to make it withstand water and be usable through 100 freeze-thaw cycles. Because the brick is solidified under pressure and not heat it is environmentally friendly, energy

efficient and costs 20% less.

Rail Brick

Rail bricks are made in the same fashion as the mud bricks before but are heated at a higher temperature and a long kiln is used with a conveyer belt running through it. Lime and ash are often spread over the bricks to speed up the firing process.

Dry Press Brick

Dry press bricks have a slightly thicker mixture than regular mud bricks and are pressed harder and fired longer to get a more accurate brick shape. Bricks with complicated designs on the sides are most often dry press bricks because the shape

holds well in the thick material.

Extruded Bricks

Extruded bricks are made with about 10-15% water for a stiff extrusion and 20-25% water for a soft extrusion. The mixture is pushed through a die and cut with wire into the proper dimensions. It’s then dried for about 40 hours and then fired. The process creates a much lighter, weather resistant brick great for structural use.

Calcium Silicate Bricks

Calcium Silicate bricks are made with lime quartz and crushed flint and used mostly for their acceptance of coloring. The materials are mixed and left to sit till the lime is hydrated. The mixture is the pressed into molds and left to sit in an autoclave to speed the chemical hardening. The finished bricks are very uniform, most often white but can

be almost any color.

Raw Materials in Bricks:

Bricks can be made from a variety of different resources including clay, shale, calcium silicate and more recently fly ash. Clay is a natural material found a few feet underground that is composed of fine-grained minerals that have a wide range of

plasticity due to varying water content. Shale (or mudstone) is basically clay and other materials that have been compacted over time and also has varying water content. Calcium Silicate on the other hand is made through combining calcium oxide and silica in different amounts. It also can absorb a large amount of water making it more malleable. Fly ash is a by-product made from burning coal in power plants. It pollutes our atmosphere if its released into the air or buried in landfills so brick making is a great use for it.

Brick Manufacturing:

There are 5 basic steps to brick making:

Digging

The first step is digging. The clay must be dug out of a mine. Most often the best clay is found beneath topsoil because it is easier to get at. It’s best to mine it out in the autumn and leave it out for a bit to expose it to the weather. The freeze-thaw cycle everyday during the autumn time breaks the clay down making it easier to work with.

Grinding

The second step is to grind and mix the clay. The clay must be ground into a fine powder and screened out to get all the rocks out. It’s then mixed with water and other chemicals to provide coloring and properties desired, then mixed to the right

consistency.

Molding

The third step is to mold it. The mixture of clay and water is then put into a mold which is usually about 2 times as wide as it is deep and long, each mould having the same dimensions as the final brick.

Drying

The fourth step is drying. Each brick is stacked together with other bricks and left to dry in the sun for 2 days. Afterwards they are checked for warping and flipped to allowing equal drying time on both sides and left for another 2 days.

Firing

The fifth step is burning or firing. The bricks are gathered from the drying area and delivered to the kiln room. They are then stacked deep into the kiln where they are fired at about 900-1000 degrees for anywhere from 48 hours to a week.

Coloring Bricks:

The color of clay bricks is related to the type of material used to create the brick, the temperature they’re fired at and the atmosphere in the kiln. For example pink bricks are made when there is a high iron content in the brick. When temperature is thevariable it goes from red to gray as the temperature increases to around 1300 degrees.

Environmental Impact of Bricks:

Bricks when made in correctly built furnaces are very eco-friendly building materials. When a furnace is made and set up with proper ventilation and trapping of pollutants it has minimal negative impact on the environment. Not only that, bricks are made from renewable resources and by-products from other processes that would otherwise be thrown out making them a very “green” building material.

Brick is a classic building material because it is strong and virtually maintenance free and never goes out of style. Unlike other building materials brick cannot be eaten by termites, burned by fire and it does not rot or corrode. Homes made of brick generally have a resale value of 6 percent higher than homes with other siding materials. Because brick is so dense it has a higher thermal mass, meaning that in the summer a brick home will stay cooler by keeping the hot air out, and in the winter it will hold the heat in.

Sometimes the outside layer of brick may be a better quality brick than the bricks making up the middle of the walls of a building. Because it is only this layer that is visible so it is more cost effective to use cheaper, softer bricks in the middle layers. During the construction of a brick building rows are called “courses” and the pattern in which the brick is lied down is called the “bond.”

Summary:

Credits:

"Brick." Wikimedia Commons, . 7 Dec 2008, 22:17 UTC. 15 Dec 2008, 21:12 <http://commons.wikimedia.org/w/index.php?title=Brick&oldid=16659008>.

"Gallery" The Siyazisiza Trust, . 15 Dec 2008, 13:07 PM. 15 Dec 2008, 13:07 PM. <http://www.siyazisiza.co.za/>.

"Main Page" The Singing Quilter, . 15 Dec 2008, 13:07 PM. 15 Dec 2008, 13:07 PM <http://www.singingquilter.com/>

NSF. "Follow the "Green" brick road?" Nsf.gov. 22 May 2007. NSF. 15 Dec. 2008 <http://www.nsf.gov/news/news_summ.jsp?cntn_id=109594&org=eng>.

Triangle Brick Company. "Faq". 16 Dec 2008 14:07 PM. <http://www.trianglebrick.com/about_faq.aspx >

Cash, Terry, and Ed Barber. Bricks. Ed. Rebecca Stefoff. Danbury: Garrett Educational Corporation, 1990.

The following members of the Wikimedia Project who donated photos to Wikimedia for our use:

BrokenSphere

lokilech

Mav