What is Architectural Precast?
Architectural precast concrete is generally defined as any precast product that contributes to the aesthetic and architectural value of the structure. Products include buildings, wall or panel systems, sound barriers, picnic tables, ornamental pieces, signs, support slabs, columns, etc.
HISTORY
Many suspect the precast concrete industry began in ancient Rome, as the extensive network of underground tunnels that exist to this day seem to indicate the use of precast building materials.
However, the documented history of the modern-day precast concrete industry began in the 1900s when an English engineer by the name of John Alexander Brodie discovered precast concrete components could come together to build a structure efficiently. Brodie was first to get a patent for the process of creating precast concrete paneled buildings.
In 1950, the first major precast concrete structure appeared in the United States — the Walnut Lane Memorial Bridge in Philadelphia. This bridge is recognized by many as the beginning of the precast concrete industry in the United States as we know it today. A few years later, the Precast Concrete Institute was formed to begin to set standards for this emerging industry.
PRECAST CONCRETE MANUFACTURING
Precast concrete is created off-site using a mold. That’s the main difference between precast concrete and site cast concrete, which is poured into its final destination on site. Here is a simplified overview of the precast concrete process:
Precast concrete is poured into a wooden or steel mold with wire mesh or rebar. This mold may also have prestressed cable, if needed.
It is cured in a controlled environment — usually at a plant.
Once finished, the precast concrete is transported to a construction site and put into place.
It’s important to note that not all precast concrete is prestressed with cable reinforcement. The addition of this reinforcement is particularly useful in many structures and buildings where maximizing the strength of the concrete is essential. The addition of the wire or rebar provides tension within the concrete, which is released once curing is complete. The release of the wire or rebar tension transfers strength to the concrete, creating an even stronger material.
Regardless of whether or not prestressing is a part of the equation, this process is faster, safer and more affordable than standard concrete. Precast concrete materials help you maximize your project’s potential while making sure it is completed on time. They are also among the most versatile products in construction, combining a strong structure with the ability to:
Choose any combination of color, form or texture
Integrate facades
Meet compatibility requirements for historic structures
Create everything from small sections to long open spans
Be recycled or reused upon removal or replacement
TYPICAL PRECAST PROJECTS
Perhaps the versatility is one of the reasons precast concrete structures are so diverse — ranging from parking garages, bridges and office buildings to stadiums, retail shops and housing. It’s clear any number of building types can benefit from the advantages of precast concrete products. Some of the most common construction projects that use precast concrete are listed below.
PRECAST CONCRETE STRUCTURES.
Since durability is one of the key characteristics of concrete construction, it’s no surprise that many precast concrete structures are used in applications that see a lot of wear and tear from everything from traffic to weather elements. Going hand-in-hand with durability is its strength — another reason it is especially popular for these applications.
Parking Structures: In parking structure design, durability, economy and installation are three key points of consideration, which is why precast concrete is usually the building material of choice. You’ll find several different precast concrete products in parking garages — columns, traffic barriers, stairs, paving slabs, architectural veneer and more. Precast concrete is useful for single-level parking structures as well as larger and more elaborate mid-rise structures.
Foundations: Precast concrete is used to create entire buildings — more about that below — but in cases where it isn’t utilized for the entire building, it may still be used for the foundation. Many residential homes and other buildings have precast concrete foundations, regardless of what is used for walls and floors in the rest of the building. Its reputation for providing a moisture-free, and energy-efficient basement is often what makes precast concrete the material of choice.
Bridges: The Walnut Lane Memorial Bridge began the precast concrete industry in the United States, and using precast concrete materials for bridges continues today. You’ll find precast concrete materials are used for beams, arches, girders, deck slabs, caps and more. Regardless of the size of the bridge, precast concrete gives engineers the ability to create a structure that blends in with the environment and is compatible with any historical surroundings.
Culverts: When you remember the underground tunnels of ancient Rome are suspected to be early signs of precast concrete, it’s easy to see how a section of modern-day underground infrastructure is the perfect application for precast concrete. Box and three-sided culverts are manufactured in all different shapes and sizes to aid in stormwater and wastewater drainage, create short bridges, retain rainwater and more. Many of them are built using precast concrete to ensure a high-quality and durable product that can be installed efficiently.
Curb Inlets and Catch Basins: Just like culverts are a part of the underground infrastructure, so are curb inlets and catch basins for wastewater management. Different states and local municipalities have different standards for these pieces, but precast concrete manufacturing can take all of them into consideration and create a product that helps stormwater runoff drain to the underground infrastructure in place.
Sound Walls: In urban areas, sound walls are erected as a noise barrier between highways and communities. Using precast concrete for these structures can cut noise pollution up to 50 percent. The versatility of design enables these sound wall structures to blend into their surroundings with a specific color, texture or design.
Retaining Walls: Many precast concrete retaining systems include segmental retaining wall (SRW) products, large precast modular blocks (PMB), mechanically stabilized earth (MSE) face panels, crib walls, cantilever walls and post-and-panel systems. Each of these elements specifications easily met in a timely fashion by precast concrete.
PRECAST CONCRETE BUILDINGS
The fire-resistant and sound-attenuating characteristics of precast concrete products make them ideal for a variety of building applications. Reducing moisture and creating an energy efficient environment are two other convincing factors when considering a precast concrete building. The diverse variety of buildings included below encompasses the versatility of precast concrete, as these materials come together to create an impressive result.
Office Buildings: The unique characteristics of precast concrete products allow for unique building designs that are attractive and functional. Take advantage of precast concrete columns paired with architectural panels to create large and open spaces.
Multi-Unit Housing: Precast concrete products have superior fire resistance — known to reduce fire insurance rates — and also act as a sound barrier. These characteristics make it a perfect choice for hotels, dormitories, apartment buildings and complexes, senior living communities and similar structures.
Hospitals and Medical Centers: For many of the same reasons precast concrete is preferred for multi-unit housing, it also provides a strong foundation for hospitals and medical centers.
Schools: Precast concrete makes school construction a breeze. With faster turnaround times from start to finish, precast concrete will keep your project on target. Whether you’re adding on to a university campus or an elementary school, you’ll get students moved in quicker without all the headaches of traditional building.
Retail Shopping Centers: Retail shopping centers vary — in rural areas, they may be built on a large plot of land, while urban areas tend to have smaller construction sites. They may or may not incorporate parking and can come in single stories, or a few stories high. Regardless of the application, precast concrete has the versatility to match, and its often used in constructing retail shopping centers. The Target Retail Center is an example of a precast retail shopping building.
Advantages:
Quality Control
Precast/prestressed concrete is manufactured in PCI Certified plants in a controlled environment.
Durability
The high-strength, high-performance concrete that is utilized in the production process resists weather, fire, corrosion, and vandalism.
Speed of Construction
Precast/prestressed concrete lends itself to compressed construction schedules. Components are manufactured off-site, allowing for a just-in-time delivery system. Speedy construction means earlier completion dates which equals earlier occupancy.
Design Flexibility
The combination of standard structural shapes and the capability of casting custom shapes gives designers maximum flexibility. Economies of scale can be achieved through repetition while the inherent plasticity of concrete allows for unique shapes.