You might be astonished by the number of architectural innovations that have occurred in the last few decades. One of the most important innovations has been the use of precast concrete.
If you’re a construction project manager, you know that precast concrete is something that has completely overturned the use of conventional cast-in-place concrete. Builders use precast concrete and other precast products in many projects because they increase construction speed and result in stronger structures.
In this article, you will learn all there is to know about precast concrete. We will examine its characteristics, benefits, and the different precast concrete structures available.
Therefore, without any further delay, let us dive into the main topic.
What is Precast Concrete?
Precast concrete is a construction material created by pouring concrete into a preshaped mold. The concrete is then left to cure in an appropriate environment. Once cured, the mold is removed and reused.
The precast concrete product is then taken to the job site and used for the project. For instance, if designed to be walls, the precast concrete walls are typically lifted into position by a crane on site.
The precast concrete method is very different from the conventional way concrete was used, cast-in-place.
In the conventional method, the concrete is formed into the desired shape at the project location and left to cure. There is no transportation involved.
A Brief History of Precast Concrete
As mentioned in the introduction, precast concrete structures aren’t a recent innovation. This technique was used in Ancient Rome to create tunnels and aqueducts.
The method evolved over time, especially in the last century. In this day and age, builders use precast concrete products to create entire building systems.
When was precast concrete invented?
While the method was used in ancient times, the credit for its modern use goes to John Alexander Brodie. He was a City Engineer in Liverpool, England. He designed buildings with precast concrete panels in the city.
How is Precast Concrete Made?
To make precast concrete structures, first, the molds are prepared. The molds are reusable and prepared in the shape that the precast concrete will have.
Once the molds are done, the concrete mix is poured into it. After pouring, the mixture is left to cure. Factors like temperature and humidity are precisely controlled during the curing process.
Once cured, the molds are removed, and the finished product is shipped to the job site.
Since the molds can be shaped in any form, precast concrete comes in many different shapes and sizes. However, when the size of products becomes larger, the weight becomes an issue. Therefore, you won’t find very large single precast concrete panels.
Materials Used in Precast Concrete
Many different components go into making a precast concrete structure. These materials include:
- Cement: This is the most important material in precast concrete. The National Precast Concrete Association sets the requirements for what quality of materials you need to use to create high-quality precast concrete as an NPCA-certified plant.
- Generally, Ordinary Portland Cement (OPC) Grade 43 and 53 are used in precast concrete. For precast concrete created for harsh conditions (such as tidal environments), Portland Pozzolana Cement and Portland Slag Cement are used.
- Water: The ratio and purity of water are key factors in creating a superior precast concrete mix design. The water mustn’t contain any impurities, as particles in water can degrade the mix quality.
- Supplementary Cementitious Materials (SCMs): These are generally industrial by-products and sometimes natural materials that exhibit the properties of cement. These are mixed in Ordinary Portland Cement to improve its hydration properties.
- Aggregate: The type of aggregate is typically chosen based on the mix design for a specific precast concrete structure. A project manager will typically consider factors such as durability, color, or texture. Special Aggregate can be used.
Some other materials added to precast concrete are:
- Waterproofing admixtures: Crystalline waterproofing admixture is one example. It makes the precast concrete products resilient to water damage. This is used in structures like septic tanks, retaining walls, roofs, etc.
- Oxides: Since precast concrete is a product ready for installation, it is sometimes produced in different colors. The color is added by using oxide pigments.
- Reinforcement bars: Reinforcing bars act as a spine for precast concrete and make the product strong. There are many different designs of reinforcing bars that may be used, depending on the structure to be created.
- Steel tendons: Tendons may be bars, wires, or strands. It is best to use steel tendons free from contamination like dust and mud to create a strong adhesion between the steel and the precast concrete. All metal reinforcements require a protective coating to prevent corrosion of the metal.
- Joints: These provide stability and strength in a precast concrete building by transferring forces to the structural elements.
- Lightweight Aggregate: This type of mix is used in many projects when a lighter concrete structure is required. Air bubbles are present in the concrete to reduce the density and overall weight of the final structure.
- Fibers: Adding fibers to concrete further reinforces the strength of the concrete manifold. Different fibers are used in precast concrete, such as steel and polymeric fibers.
- Non-shrink Grouts: Non-shrink grouts are generally used to shift the forces between different structural elements.
- Epoxy Grouts: The purpose of adding epoxy grouts to precast concrete is to create precast concrete with a very high strength profile. Adding these grouts requires expert supervision since the properties of different epoxies can vary significantly.
What are the Benefits of Using Precast Concrete?
There are many benefits that using precast concrete offers as opposed to conventional building materials like cast-in-place concrete. Some of these benefits are:
The most important benefit of using precast concrete is that it considerably speeds up the construction process for any project. Ordinarily, builders used to pour concrete on the job site and wait for it to cure, which could take several days or weeks.
With precast concrete, they can simply order ready-made precast products as per their requirement and fit them in place. There is no waiting period involved at all. Reputable brands like Premier Precast always have precast concrete structures in their inventory.
Precast concrete brands like Premier Precast include carefully chosen materials in their mixes, which you saw in the list above. Adding these elements results in characteristics like high strength, waterproofing, etc.
When curing concrete on the site, many of these materials are difficult to procure and may be forgotten or overlooked. Therefore, precast concrete has a significantly higher strength than an ordinary concrete surface.
Precast concrete is manufactured in facilities where the curing happens in a carefully controlled environment. However, when curing concrete at the construction site, nobody can control the environmental factors such as rain, humidity, heat, etc.
Precast concrete manufacturers are solely focused on the aspect of creating concrete. Therefore, there is a greater quality control resulting in consistent products.
However, on sites with large-scale projects, there is so much work going on that no one can monitor the quality control of cast-in-place concrete at all times. This can lead to low quality and inconsistent construction. For more information, read our in-depth comparison of precast and cast-in-place concrete.
For construction projects, speed is of the essence. Every day lost can add costs in labor and resource waste. By speeding up the process using precast concrete, builders can save a lot of money on the cost of labor and other things.
Precast concrete is created using specialized molds designed for the purpose. Manufacturers create these molds in many different shapes and sizes because they can be reused.
There are options for builders to order precast concrete structures with complex decorative elements. These elements cannot be created on the construction site with cast-in-place concrete due to the significantly high costs of designing and creating specialized molds.
What are the Characteristics of Quality Precast Concrete?
The benefits of precast concrete are applicable if you are using good-quality precast concrete. Otherwise, your money might be wasted, and the time you save amounts to nothing since it will lead to repair requirements in the future.
Here are some of the characteristics of good precast concrete that can help you make an informed choice:
The purpose of precast concrete is to be used as it is. Therefore, the concrete size you order should be the size you get. In general, precast concrete has good dimensional accuracy.
The final product has a high consistency when precast concrete is created using high-quality materials and a controlled environment. If your precast concrete structures are inconsistent, you may be using precast concrete of inferior quality.
Good precast concrete does not contain any VOC. VOC in concrete leads to mold and foul odor, common in residential buildings. Therefore, use good precast concrete, and the buildings will be resilient to molds and unhealthy indoor environments.
What are the Different Types of Precast Concrete Structures?
You would be surprised at the number of precast products the industry offers nowadays. The options are so many that you can complete your entire building with precast products.
Here are some of the precast products that builders use nowadays:
Precast Concrete Walls
Precast concrete panels and walls can be used to create both residential and commercial buildings and complexes. These walls come in different sizes and can be designed according to the needs of any project.
These walls also have high reinforcement and can serve as retaining walls and creating septic tanks where required.
Precast Concrete Slabs
Precast concrete slabs are multipurpose and can be used to create elements such as stairs and ceilings. The slab dimensions (including thickness) can vary based on the requirement of the project manager or builder.
Precast Concrete Beams
Precast concrete beams and girders are available with reinforcement in these elements. These are used in creating the framework of many commercial construction projects.
The precast concrete industry even offers columns you can order with a single click instead of making them on-site. Using precast columns is better than using fresh concrete for your elevation requirement.
Yes, you read it right. You can buy ready-made elements for use in utility buildings like precast concrete stairways and even individual steps instead of making them on-site. These stairs are used in various structures such as homes, malls, office buildings, etc.
Besides these structures, the precast concrete industry also offers specialized precast concrete products like:
- Double Ts
- Bridge beams
- Septic Tanks
- Hollow-core slabs
And many more.
How to Source High-Quality Precast Concrete Products?
When you buy precast concrete products, there are many different options you will find out there. However, those options become limited when you have stringent quality requirements for precast concrete.
The National Precast Concrete Association has set requirements that precast concrete should meet. Only an APA-certified or NPCA-certified plant can meet these requirements for production practices and quality.
Then there are manufacturers like Premier Precast, constantly evolving and setting the bar higher and higher. As an award-winning business, Premier Precast provides diverse concrete solutions, including an extensive product line in precast concrete.
Premier Precast not only meets the National Precast Concrete Association requirements but is actually certified and licensed for every precast product we offer.
Some of the precast concrete products and other architectural materials that you can find at Premier Precast include:
- All precast products mentioned above, such as precast concrete stairs
- Architectural precast concrete
- Cast stone
- Natural stone
- Manufactured Stone