Precast concrete is renowned for its advantages over other construction methods, mainly site-poured concrete. Some of these advantages include its ease of use, cost-effective nature, and its durability. However, simply mentioning these benefits isn’t enough. It is important to quantify these benefits against alternative construction methods.
Therefore, this article will have a detailed discussion on precast concrete durability. With the information presented here, you will know the strength of precast concrete products and find out whether they are durable enough to handle your requirements.
Precast Concrete Overview
Precast concrete is a method of using concrete where the raw materials are mixed and poured into different shapes of molds. The concrete is then cured in the highly controlled environment of the factories and with high-quality control. The builders can order the cured concrete slabs directly choosing from a multitude of shapes and surface finishes. The precast concrete slabs are delivered to the doorstep instantly.
Since the concrete that builders order is cast and cured in a precast plant beforehand, it is also known as prefabricated concrete or pre-made concrete. Precast concrete is quite different from the traditional construction method- pouring concrete onsite and waiting for weeks so it can cure in uncontrollable environmental conditions.
How Strong is Precast Concrete?
Precast concrete is considerably stronger than site-poured concrete. The main reason for its higher strength lies in the higher quality of materials, some of which cannot be locally sourced, and the curing process in a highly controlled environment. Additionally, for structural components, the strength of precast concrete products is increased further by adding prestressed steel strands. This concrete is then known as prestressed concrete.
What is the Compressive Strength of Precast Concrete?
The compressive strength of concrete is the amount of load that it can withstand before failure. It is the best way to know how strong any particular concrete panels are. For precast concrete with steel strands, the compressive strength is about 7,000 psi (48 MPa). This concrete can withstand loads of more than 100,000 pounds, which is an astonishingly extreme value. Therefore, it is ideal for any type of construction including high-rise buildings. Even without any steel strands, conventional precast has a minimum concrete compressive strength of around 4500 psi (31 MPa).
Keep in mind that to obtain these high values of compressive strength, it is important to use quality precast concrete components. Premier Precast is the industry leader when it comes to high-strength precast concrete production, testing the products and materials before delivering them to you.
Is Precast Concrete Stronger Than Other Types of Concrete?
Yes, precast concrete is much stronger than other concrete types, such as traditional concrete with on-site pouring. In fact, precast concrete construction is also more durable and faster when building than cast-in-place concrete. In fact, experts even regard precast concrete as the not only the more durable option, but also the one using higher sustainable materials (MK Hurd).
What Makes Precast Stronger Than Other Types of Concrete?
There are many reasons that add to the strength and durability of precast over cast-in-place concrete. Here are some of these factors:
The quality of concrete is mostly dependent on how it is cured. Even using the highest material quality can be useless if curing concrete is not done in the proper environment. For cast-in-place concrete, there is no control over the environment so the desired curing process is not possible.
However, for precast concrete, the curing is done indoors in a carefully controlled environment. There is a complete handle on factors such as humidity and temperature. This leads to ideal curing conditions for concrete, enabling it to show its full potential strength.
Professionals working with cast-in-place concrete often forget about permeability, which is a huge factor in determining the durability of this construction material. Permeability means the ability of concrete to allow the passage of water through the pores. If the concrete has a higher permeability, the water will seep inside and lead to the corrosion of the steel reinforcement within the concrete. Therefore, it is important for the concrete to have low permeability.
However, precast concrete employs the latest technological measures for proper mixing of concrete to ensure an extremely low permeability. There is no seepage of water in the concrete pores, so corrosion of the reinforcements is never really a concern for precast concrete. Additionally, besides the low permeability, the mixing technologies used in precast concrete also minimize voids, which leads to denser concrete with increased strength.
Precast concrete contains several chemical additives so the panels can have resistance to weather, acids, alkalis, ASR reactions, seawater corrosion, sulfate attacks, and many other harmful elements. Adding these aggregates is not possible for cast-in-place concrete due to sourcing difficulties or cost restraints. However, precast concrete utilizes economies of scale, so it is possible to use all the best-desired materials without raising the cost significantly.
There is even thermal insulation added inside the precast wall panels to ensure that it is resistant to hot and cold temperatures without the need for secondary outer insulation. Other additions such as sound insulation and fire resistance are also added within the concrete product itself.
The long lifespan is another one of the precast concrete advantages. Precast products are designed to last for at least 100 years once installed. Additionally, they do not require any Maintenance or repairs during their lifetime. This is very different from a conventional concrete mix where the end product is expected to last a few decades after which it needs significant repairs.
What are the Precast Concrete Standards?
For precast concrete which is not prestressed, a minimum compressive strength of 4500 psi (31 MPa) in 28 days is mandatory. In case the concrete is prestressed, it needs to meet multiple requirements such as:
- The maximum allowed water-to-cement ratio is 0.40.
- The minimum 28-day compressive strength should be 5000 psi (34.5 MPa).
- At the time of prestressing, the concrete should have a minimum compressive strength of 4000 psi (27.6 MPa).
- Demonstrate the initial tension of prestressing steel in the plans.
As the numbers dictate, precast concrete has significantly more durability and strength as compared to that poured on the construction site. This is why the majority of builders are using precast concrete for every type of manufacturing requirement.
Premier Precast of Delray Beach Florida specializes in precast concrete solutions. It is one of the leading precast manufacturers in the US that can provide customized precast concrete panels in any shape, size, and surface finish you require.
Contact Premier Precast for a free design consultation/ quote on any of your precast needs.
Frequently Asked Questions
Here are the answers to some common doubts that people have regarding precast concrete:
1. Does precast concrete crack?
Precast concrete is less prone to crack. Cracks in concrete occur when curing outdoors due to heat changes, winds, curing rate, humidity, or other environmental conditions. Another reason for the cracks is a high water-to-cement ratio. These factors are not present in the manufacturing of precast concrete products.
2. Are precast concrete walls load-bearing?
Yes, precast concrete walls can be load-bearing. Prestressed concrete wall panels can handle a load of over 100,000 pounds. Even higher load-bearing capacity is possible by adding specific reinforcements and using particular designs.