Precast concrete is renowned for its advantages over other construction methods, mainly poured concrete on the job site. Some advantages include its ease of use, cost-effective nature, lower energy consumption, and durability. However, simply mentioning these benefits isn’t enough. So let’s quantify and compare the aspects of precast concrete strength to alternative construction methods.
This article discusses precast concrete’s durability in detail. With the information presented here, you will know the strength of precast concrete products and whether they are durable enough to handle your requirements.
Precast Concrete Overview
Precast concrete uses raw materials mixed and poured into different shapes (slabs, panels) using a mold. The concrete then cures in a highly controlled environment for optimal quality. Builders can order the cured concrete slabs or panels, choosing from a multitude of shapes and surface finishes, and get the precast concrete slabs delivered to the doorstep.
Since the concrete that builders order is cast and cured in a precast plant beforehand, it is also called prefabricated concrete or pre-made concrete. Precast concrete manufacturing offers greater control than the traditional method of pouring concrete at the job site 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 superior 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 a precast concrete structure can be 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 load it can withstand before failure. It is the best way to know the strength of concrete structures. The compressive strength of precast concrete with steel strands is about 7,000 psi (48 MPa). This concrete can withstand loads of more than 100,000 pounds, which is an astonishingly high value. Therefore, it is ideal for any construction, including high-rise buildings. Even without reinforcing strands, conventional precast has a minimum concrete compressive strength of around 4,500 psi (31 MPa).
Keep in mind that to obtain these high compressive strength values, it is important to use quality precast concrete components. Premier Precast is the industry leader in 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 types of concrete, such as traditional pouring concrete on site. Precast concrete construction is also more durable and saves more construction time than using formwork and cast-in-place concrete onsite. Experts regard precast concrete as the most durable option, and it uses more sustainable materials (MK Hurd).
What Makes Precast Stronger Than Other Types of Concrete?
Many factors add to its strength and durability, giving precast concrete advantages over cast-in-place concrete. Here are some of those factors:
The quality of concrete is mainly dependent on the curing process. Even with the best material quality, if the process of curing the concrete isn’t strictly controlled, then the results may be less than perfect. In the case of cast-in-place concrete, there is little control over the curing environment, so an optimal curing process is impossible.
However, for precast concrete, the curing takes place indoors in a carefully controlled environment. Factors such as humidity and temperature are optimal, providing ideal curing conditions for the concrete, and enabling it to achieve its maximum potential strength.
Professionals working with cast-in-place concrete often forget about permeability, which is a huge factor in determining the durability of any construction material, whether brick, stone, or concrete. Permeability measures how much water can pass through the pores of a material. Concrete with high permeability would allow water to seep inside and lead to the corrosion of the steel reinforcement within it. Therefore, concrete must have low permeability.
Precast concrete manufacturing employs the latest technology and techniques to ensure the proper mixing of concrete, resulting in extremely low permeability. There is no water seepage via the concrete pores, so corrosion of the reinforcement strands or bars is not a concern. Additionally, its low permeability and the mixing technologies used in precast concrete minimize voids, resulting in denser concrete with increased strength.
Precast concrete contains several chemical additives, so the panels are resistant to weather, acids, alkalis, ASR reactions, seawater corrosion, sulfate attacks, and many other harmful elements. Adding these aggregates is impossible for cast-in-place concrete due to sourcing difficulties of some chemicals or cost restraints. However, precast concrete utilizes economies of scale, so it is possible to use all the best materials without significantly increasing the cost of a project.
The use of concrete and EPS foam in manufacturing precast wall panels results in excellent thermal insulation properties. They resist hot and cold temperatures and do not need secondary outer insulation. Other additives within concrete products improve properties such as sound insulation and fire resistance.
Its 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. In contrast, with a conventional concrete mix, 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 4,500 psi (31 MPa) in 28 days is mandatory.
In the case of prestressed concrete, 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 5,000 psi (34.5 MPa).
- At the time of prestressing, the concrete should have a minimum compressive strength of 4,000 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 than concrete poured at the construction site. These factors are why many builders use precast concrete for most building requirements.
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 for your next project.
Frequently Asked Questions
Here are the answers to some common questions that people have regarding using precast concrete:
Does precast concrete crack?
Precast concrete is less prone to cracking. Cracks in a concrete building occur when curing outdoors due to heat changes, winds, curing rate, humidity, or other environmental conditions. Another reason for cracks is a high water-to-cement ratio. These factors are not present in the manufacturing of precast concrete products.
Are precast concrete walls load-bearing?
Yes, precast concrete walls and columns 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 design elements to a concrete product.