Burnt clay bricks are the most common brick in the United States. They are simply made by pressing wet clay into pre-formed molds to give them the desired shape and size. After being pressed into the molds, the bricks go through a short drying process before being fired in a kiln.
Burnt clay bricks in combination with concrete bricks (cmu) are used for almost all residential foundation and veneer projects. This includes masonry porches, columns, and brick fencing also. It’s what we use 90% of the time here at Four Oaks Residential.
Also known as “Refractory” brick, fire bricks are used in high heat applications such as in fireplaces, fire pits, lining furnaces, kilns, chimneys and fireboxes. Fire brick are made mostly from fire clays or hydrous silica and alumina.
Fire brick is manufactured in a similar way to burnt clay bricks, but with drastically increased kiln temperatures. They are fire proof, great insulators, and are extremely durable. They have a compressive strength of around 2,800 pounds per square inch.
Calcium silicate (Sand Lime) bricks are primarily used in Europe for residential construction. It consists of simply water, sand, and lime. With no added chemicals, or toxic byproducts, sand lime bricks are gaining traction in European countries for health and environmental reasons.
The aerated brick manufacturing process is unique and uses an autoclave for the curing process. Sand lime bricks are most often used in the construction of foundations, walls, and exposed pillars due to their strength as a load-bearing member.
There are two grades of engineering brick, “Class A” and “Class B”. Engineering bricks are typically used in civil projects for areas where protection against water penetration and frost attack are critical.
Think sewer systems, retaining walls, tunnels, churches, office buildings, and other structures that require extreme compressive strength and water protection. Compromised of clay with approximately 15% moisture and fired at over 1,800 °F!
Class A engineering bricks are the strongest and most resistant to moisture penetration. Also known as the “Staffordshire Blue”, class A bricks are dark blue in color due to the extremely high temperatures used in the manufacturing process. These super bricks have a compressive strength of over 18,000 lbs sq/in! Take a look at Ketley Brick’s site for beautiful examples of buildings built with Staffordshire blue brick.
On the other hand, you have “Class B” engineering bricks, which are more commonly used than the class A designation. A noticeable difference in appearance is the fact that class B brick are typically red in color. This is because the brick are fired at a lower temperature than the grade A brick. The compressive strength of class B brick is around 11,000 lbs sq/in.
Fly ash is a waste byproduct of coal combustion in thermal power plants. So that makes fly ash bricks an environmentally friendly brick; one that rids the ground of toxic waste. They are typically used in multi-story buildings for interior and exterior walls (some load bearing and some non load bearing).
Another excellent quality of fly ash brick is its built in earthquake resistance and commonly is used in warmer climates due to it’s low heat absorption properties. It keeps your home much cooler in the summer.
This brick requires less labor to install, less mortar mix, and is somewhat lightweight. Perhaps, the savings in weight paired with its high compressive strength is the reason it is often used in multi-story building construction.
A lower quality form of burnt clay brick that is cured by the sun instead of in a high heat kiln. Also known as “mud bricks”, sun dried bricks are made by packing mud (mostly clay) into premade forms and are left outside to dry or cure in the sun. In some countries, straw is added to increase the strength of the bricks.
As you can imagine, sun dried bricks are inferior in almost every way to the standard burnt clay brick, although they have their place in construction. They are most widely used in constructing small one or two room houses in third world countries that have very low structural requirements.
A form of brick made with concrete into what most of us recognize as a concrete block. They are made by mixing cement and sand / limestone into a mold and cured in a variety of ways. Some of those ways include: autoclave curing, membrane curing, steam curing, and wet curing.
All residential crawlspace foundations are built using concrete brick/block. It can be paired together with a traditional burnt clay brick exterior to offer a more refined appearance and a seamless transition to your home’s masonry veneer. The compressive strength in a medium density concrete brick is approximately 1,800 psi and a higher density concrete brick has a strength of 2,500 psi. If you need to hire a contractor, you should read our article “How to Hire a Contractor”.
One of the most interesting things to me about bricks is the fact they they are all different, not completely but they all serve their own unique purpose. The art of masonry has been utilized for almost 6,000 years starting with the sun dried clay bricks that we talked about earlier. With the invention of new hybrid materials, it’s interesting to see where the world of masonry will take us next.