How Precast and Custom Concrete Buildings Are Made

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Large precast concrete blocks laying next to each other on a job site

Take a look at any industrial, commercial, or even residential area, and you’ll see concrete everywhere.

It’s one of the most popular building materials in the construction world because it’s high strength, low maintenance, and energy-efficient.

Concrete is also highly versatile. There are many different styles of concrete structures, each with a defined building process and application.

Here is a breakdown of how the most common types of concrete buildings are made. We’ll also discuss when each of these types should be used in a construction project.


Concrete Block Buildings

Concrete block buildings are also known as concrete masonry units (CMUs). These buildings are made by stacking hollow or solid concrete blocks to form exterior (and sometimes interior) walls.

If the blocks are hollow, steel rods or more concrete can be added into the holes for reinforcement.

There are several different sizes and types of blocks that can be used. Textured ones can add a nice facade to a building. Check out the list of the blocks available here.

How Concrete Block Buildings Are Made

Here’s what the process of constructing a concrete block building looks like:

Step 1: The construction crew puts down a moistened strip footing as a base for the concrete blocks.

Step 2: A straight line is chalked out or delineated with string to use as a construction guide.

Step 3: The crew lays out the blocks to ensure a proper fit is established.

Step 4: The blocks are removed and one inch of mortar is applied to the footing.

Step 5: Starting from the corner, blocks are laid down with mortar in between each one.

Step 6: The process is repeated vertically, with mortar applied between each layer until the desired height is reached.

Step 7: Adjustments are made to each layer to ensure they are aligned vertically and horizontally.

Step 8: Once the mortar is semi-hardened, excess mortar is cleared.

When to Use Concrete Block Building Construction

This type of concrete construction is strong and easy for professionals to build. Because it is set on a secure footing, concrete block buildings shift much less than other types of concrete buildings.

The blocks are easily maneuverable and cheaper than other concrete panels. Even so, the process takes a little more time to complete.

Concrete block structures are most commonly used as security barriers and in chimneys and fireplaces. They are also used as retaining walls, load-bearing walls, and partition walls.

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Precast Panel Concrete Buildings

Precast concrete buildings are another popular and efficient option.

Although many people think precast concrete architecture is a novelty of modern engineering, Romans used precast panels to construct the aqueducts and catacombs centuries ago.

Concrete panels are cast in a climate-controlled location, which helps cut down on the time it takes to finish the project since the weather does not interrupt the process.

The forms are cast in a pre-made mold in an assembly line with robotic equipment.

The curing of the concrete happens in a climate-controlled environment. Extreme care is taken to prevent air bubbles and keep dust away, ensuring the concrete is of the highest quality.

How Precast Concrete Buildings Are Made

Here’s how precast concrete buildings are built:

Step 1: A mold or framework is made to the desired size and shape.

Step 2: Rebar cages are made to fit inside the frame.

Step 3: Concrete is poured into the mold with the rebar cage placed inside.

Step 4: Anchors made from steel loops are embedded into the concrete.

Step 4: The concrete is left to cure.

Step 5: A crane is used to lift and place the precast concrete forms into the correct position.

Step 6: The concrete forms are connected with a steel rod placed through their pre-embedded loops. Bolts may also be used to join concrete panels.

When to Use Precast Concrete Construction

Precast concrete is frequently used to make hotels, motels and, low-to-mid-rise apartment buildings.

Due to the strength of precast concrete panels, this construction method is often used for structural systems such as beams, foundations, and columns.

Precast panels are used for vaults, tunnels, and other underground structures because they can be made in a clean environment and transported underground.

They are also used as cladding panels to add style and texture to building exteriors.

Precast construction is also used to make concrete products for purchase, such as water tanks, water pipes, and sewer tanks.

Related: Your Guide to Flatwork, Applications, and What to Expect


Tilt-Up Panel Concrete Buildings

Large concrete walls propped up in place on a construction site

The tilt-up concrete construction process has the most efficient setup of any concrete method.

New buildings can be erected and enclosed with a handful of workers in a matter of days.

According to Thomas Edison himself, this process eliminates the cost and effort of erecting a concrete wall.

With this building option, forms are set in place and filled with reinforced concrete, then tilted up in a vertical position when ready.

This process is similar to precast construction, only the forms are much larger and must be made on site.

How Tilt-Up Concrete Buildings Are Made

Here’s how construction teams build concrete buildings:

Step 1: Entire walls are framed out with wood and reinforced with rebar.

Step 2: Concrete is poured into the frame and cured.

Step 3: Walls are tilted up (hence the name) onto a solid foundational footing.

Step 4: Panels are braced until the roof is attached, holding all pieces together.

When to Use Tilt-Up Concrete Construction

Tilt-up construction is best for large commercial buildings, as savings increase with the project’s square footage.

Warehouses, distribution centers, and shopping malls are the perfect project for tilt-up concrete construction.

Building a warehouse? Steel could be a better option for you. Learn why in this article: 7 Benefits of Choosing Steel for Warehouse Construction.


Insulated Concrete Buildings

Insulated concrete forms, or ICF, are buildings made from concrete poured into expanded polystyrene (EPS) molds.

The double layer of insulation around the concrete ensures these buildings are well insulated and well sealed, making them a great choice for energy efficiency.

Also, the life cycle of this building material is well over a hundred years, so they’re a sustainable way to build.

How ICF Buildings Are Made

Here’s how ICF buildings are constructed:

Step 1: Strong insulation blocks with plastic webbing inside are connected together to form the exterior of the building. The blocks interlock to form airtight connections.

Step 2: This form is filled with concrete and cured.

Step 3: Exterior siding can be added to the insulation for aesthetics.

When to Use the ICF Building Method

The insulated concrete form method is best used for residential homes.

This type of construction tends to stay at a comfortable temperature, helping homeowners reduce heating and cooling costs.

You can even use thicker insulation to increase the structure’s energy efficiency, which is especially helpful in locations with extreme temperatures.

In most cases, ICF exceeds building codes, making for an ideal living space.


Shotcrete

Shotcrete is wet concrete that is sprayed onto a backing surface. The velocity of the spraying compacts the cement, increasing its density and strength.

Shotcrete was invented by Carl Akeley, who is best known for his taxidermy. He developed the material to be shot out of double-barrel guns over the skeletal remains of animals.

Later on, in 1907, he used his invention to recoat the Field Museum of Chicago. Since then, shotcrete has been adapted for many other uses, including construction.

How Shotcrete Is Applied

There are two methods of shotcrete application: a “wet” method and a “dry” method.

In both methods, an air compressor is used to shoot cement through a hose with a special nozzle at a high velocity onto a solid surface.

In the wet method, all the ingredients are mixed together before they are shot through the nozzle. This type of shotcrete is also known as gunite.

In the dry method, dry concrete is shot out of the hose. Water is introduced through another pump as the concrete exits the hose.

Curing shotcrete is where things can get tricky. The recommended curing method is to spray with water for seven days, but a couple of layers of curing membrane can be used as an alternative.

When to Use Shotcrete

Shotcrete or gunite is most often used for curved surfaces, such as swimming pools, tunnels, water tanks, and curved architecture, like domes or arches.

It can also be helpful in covering overhead surfaces with concrete since the hose’s velocity allows it to apply material to high areas. No climbing necessary!


Cast-in-Place Concrete Buildings

Cast-in-place concrete buildings are also known as removable forms, site-cast forms, or poured concrete buildings.

This is the most traditional concrete construction process. This process happens entirely on the construction site and involves pouring ready-mix concrete into molds.

This process was originally used for building below-ground walls for foundations and cement basements, but Thomas Edison showed that it could be used for all of a home’s walls.

He began a company called Portland Cement, and some of the houses he erected are still standing to this day in Gary, IN, and Montclair, NJ.

Although Edison’s concrete vision didn’t catch on in his time, he was certainly onto something. According to the NAHB, there were more than 86,000 concrete homes in 2019, and the numbers are steadily increasing.

How Cast-in-Place Concrete Buildings Are Made

Here’s how cast-in-place buildings are built:

Step 1: Temporary forms are erected on site.

Step 2: Reinforcement, such as rebar or wire fabric, is installed.

Step 3: The ready-mix concrete is poured into the forms.

Step 4: The forms are removed when they fully cure.

When to Use Cast-In-Place Concrete

Many contractors have no choice but to complete all construction onsite. Site-cast forms are a good option in these instances.

Cast-in-place is also the best choice for areas prone to earthquakes since the structures require fewer joints, which tend to be vulnerable to stress.

Related: Is Steel Stronger Than Concrete?


Autoclaved Aerated Concrete Buildings

Construction worker laying autoclaved aerated concrete blocks on top of each other with mortar in between them

Autoclaved aerated concrete, or AAC, is a special type of construction material made from cement mixed with an expansion agent.

The resulting forms are 80% air, making them light but still strong.

How AAC Is Made

Step 1: Cement, fine aggregate, and expansion agent are mixed and poured into molds.

Step 2: This mixture expands and rises like bread dough to fill the molds.

Step 3: Blocks or panels of these forms are pieced together with grout to shape the desired building.

AAC is often mass-produced into pre-made forms. Special sizes or shapes are available, including tongue-and-groove forms, hollow blocks, and U-shaped forms for beams.

Concrete has been used for various construction purposes since the earliest days of structural engineering.

As engineering evolved, concrete construction evolved alongside it to meet the needs that arose.

Concrete is here to stay. The benefits offered by reinforced concrete buildings are too hard to ignore.

From bug and fire resistance to energy efficiency and sustainability, the argument for concrete as a viable option is obvious.

Add in the low maintenance needed to keep these buildings clean and functional, and there’s no doubt that when you choose concrete, you’re in for a win.

Planning a commercial construction project in Colorado? Call FMP for a job quote!