Published on September 1st, 2016 | by Aisha Abdelhamid
Bricks – The ABCs of Green Building Materials
In terms of sustainability and green building materials, brick is probably king. The process of making fired clay bricks has been around for over 5,000 years and just keeps getting greener. Today’s brick kilns use about 70 percent less energy to fire bricks than just 50 years ago.
Brick is a term usually referring to red-colored, fired clay units composed of sand, lime, and soil containing clay or shale. Firing bricks in a kiln renders them one of the strongest and longest-lasting building materials on earth. Still made from Earth’s most naturally abundant materials, bricks are 100 percent recyclable. Modern building codes even allow carefully recycled clay fired bricks in new building construction.
Archaeological Evidence for the Earliest Fired Clay Brick
Winding its way through ancient civilizations, “baked” or fired clay bricks have been discovered in Ancient Egypt, China, and the Indus Valley. Among the earliest archaeological sites documenting fired clay brick in use, Harrapa was once the center of the Indus Valley Civilization (IVC), which extended from today’s northeastern Afghanistan into Pakistan and northwestern India.
Aurangzeb Khan, in Bricks and Urbanism in the Indus Valley Rise and Decline, documents the earliest archaeological evidence of baked bricks at Harappa, Mohenjodaro, and other urban centers of the IVC. Khan reports the rise of baked bricks around 2,600 BCE, still visible today at Mohenjodaro in Punjab, Pakistan.
Exploring Bricks, Blocks, and Butts
Unfired brick, also known as adobe, is far more ancient than fired brick. Dried in the sun, adobe bricks have straw or other organic, fibrous material added to the composition for imparting greater strength.
Sometimes blocks are referred to as bricks, but blocks are typically larger units than bricks. Blocks are also more commonly made from cement-based concrete products, although modern brick sometimes utilizes cement, too.
Research is always underway to find new opportunities for this popular product. I like an interesting idea from an engineer at Australia’s RMIT University. Dr. Abbas Mohajerani has found a way to recycle cigarette butts into bricks, making them lighter and offering better insulation than regular brick. It’s probably easier to quit smoking than to build a recycling market for cigarette butts, however… What do you think?
Brick is the King of Green Building Materials
With a wide variety of types, uses, colors, compositions, and a huge range of applications, brick is king of green building materials.
Brick provides an energy-efficient building envelope due to its thermal mass. Taking advantage of this benefit helps reduce peak heating and cooling loads, potentially reducing HVAC system size. Brick is also fire and impact-resistant, and provides significant soundproofing benefits.
Environmental impacts can also be reduced by using brick. Most brick is manufactured from natural materials located in the near vicinity of brick plants, as opposed to transporting materials from far distances. Brick is also easily recyclable, dramatically cutting down on construction waste.
Here is a sampling of several types of bricks available today:
• Baked/Fired Clay Brick — Fired clay brick is made from soil containing natural clay or shale. The presence of iron in the soil is responsible for giving fired brick its red color. When brick is heated to temperatures over 1,000 degrees Fahrenheit, the clay particles fuse into a rock-like bond that is even stronger than concrete. Fired clay brick can last for multiple hundreds of years, never molding or rotting. It is also non-combustible, does not emit toxic fumes, and except for aesthetic reasons, does not need to be painted.
• Calcium Silicate Brick — Rather than clay, calcium silicate brick is made with lime, sand, silicate material, and a mineral colorant. This type of brick is called “chemically set,” as opposed to fired. They are typically cured in an autoclave to speed up the chemical hardening process.
• Clay Fly Ash Brick — Fly ash is used in combination with clay, lime, and sand to produce this brick, reducing the amount of soil used. Because fly ash is a by-product of coal combustion, it is considered a recycled product. However, coal combustion is responsible for CO2 emissions that are causing global warming, so fly ash use is highly problematic
• Concrete Brick — Available in many colours, concrete brick is made with sulfate-resisting Portland cement or an equivalent. They are similar to fired clay units in size, density, thermal properties, and sound resistance, but need movement joints every 16-19 feet because they expand and contract more.
• Fly Ash-Stone Powder-Cement Brick — This brick is made with fly ash, lime, cement (or gypsum), and sand/stone dust/chips. Pigments can be added to produce color variations. Reducing the use of fertile clay soil is one reason for making this kind of brick, but fly ash use is not an environmentally friendly alternative, as it is a by-product of coal consumption. This chemically-set brick can be air cured or cured in an autoclave.
• Organic/Bio-Brick — More experimental than practical at the moment, many innovative organic/bio-bricks are making a bit more headway than Dr. Abbas’ cigarette butt bricks. The BioMason, for example, makes a zero emissions brick made without heat or clay. Injecting sand with microorganisms initiates a process similar to natural coral growth. After four days of growing in an irrigated brick mould, the bricks “are strong enough for use in houses, commercial buildings, and other structures.” Another type of bio-brick is grown from a combination of agricultural by-products, like corn stalks, and a natural glue made from mushroom mycelium.
Bricks Are Green, But the BIA is Greenwashing
The US Brick Industry Association (BIA) has adopted a great environmental policy. It states:
“…we are committed to manufacturing products that provide exceptional energy efficiency, durability, recyclability, and low maintenance with minimal impact on the environment from which they originate.”
However, I have some reservations about the BIA’s political agenda: using “relationship building” to assist Republican efforts to kill the “EPA’s burdensome emission standards.”
The BIA states, “The Brick Industry Association’s Environment Health and Safety department launched a letter writing campaign to garner support for the [BRICK act] bill in the full House vote. In total there were 660 letters that were sent to 192 members of Congress.”
BIA efforts paid off and the BRICK act was spearheaded by Super-Bully Rep. Bill Johnson (R-Ohio), who charged, “Forcing brick and tile companies to comply with a costly, job-killing rule that is still pending in the courts makes no sense.” Johnson complained that EPA compliance would force brick plants “to pay for control equipment that provides no return on investment.”
Rather than hypocritically celebrating Bill Johnson and the House passage of the BRICK Act (H.R. 4557) on March 3, 2016, the BIA would do better to honor its own environmental policy which concludes:
“We will ensure that our facilities meet or exceed state and federal environmental regulations, and we will continue to partner with building professionals to help them in using our products to create environmentally responsible living and working spaces for today’s and future generations.”
The BIA clearly needs to get over it and green up. Climate change will put us all out of work if we don’t get to work fixing it.
Let’s Take a Quick Brick Workshop!
Check out this great video of a brick workshop held at the Faculty of Architecture, CEPT University, in Ahmedabad, India:
“In a span of 3 weeks, with concentrated group efforts over 6 days, the construction of a twisted pier, a twisted arch, a buttress wall with an arch and two pockets of seating space were designed and constructed.”
–Don’t forget – watch for new posts every week in our new series, “The ABCs of Green Building Materials.” And if you’d like to give a shoutout for a project highlighting great green building materials, please add a comment below!