Precast Concrete Construction Methods - Explained By Converge

March 8, 2023

Precast concrete construction methods offer several advantages over traditional on-site concrete construction. The manufacturing process allows for greater control over the quality of the concrete, resulting in a more consistent product. Precast components are also more durable and resistant to weather and wear, and can be designed to meet specific safety requirements, such as for seismic or hurricane resistance.

In this blog post, we will give an overview of precast concrete construction and the different methods. 

Read more: Precast concrete: the complete guide.

Overview

Precast concrete construction methods involve creating building components off-site in a factory or manufacturing facility, and then transporting them to the construction site for assembly. These components include walls, floors, beams, columns, and other building elements. 

Precast concrete offers a range of benefits including speed of construction, improved quality control, reduced on-site labour requirements, and the ability to create complex shapes and finishes.

The process begins with the creation of moulds or forms, which are used to shape the concrete into the desired components. Once the concrete is poured into the moulds, it is allowed to cure for a specified period of time, typically 28 days. During this time, the concrete gains strength and durability.

Once the concrete has cured, the precast components are removed from the moulds and transported to the construction site. 

Read more: Optimise precast concrete.

Different methods

Precast concrete is a construction technique that involves the production of concrete components in a controlled factory environment and their transportation to the construction site for installation. This method offers numerous benefits, including improved quality control, faster construction times, and reduced on-site labour costs. 

Common methods to create components to meet specific requirements for different projects are:

Wet-cast method

The wet-cast method is the most common method of precasting concrete. In this method, a mould is created for the desired shape and size of the concrete element. The mould is then filled with wet concrete that is vibrated to remove any air pockets and achieve proper compaction. Once the concrete has set, the mould is removed, and the product is cured in a controlled environment to ensure proper strength development.

  1. Dry-cast method

The dry-cast method, also known as zero-slump concrete, is a process where the concrete is compacted by external vibration without the addition of water. This method is mainly used for the production of large, complex shapes, such as hollow-core slabs and concrete pipes. Dry-cast concrete is denser and more durable than wet-cast concrete, making it suitable for heavy-duty applications.

  1. Precast prestressed concrete method

In the precast prestressed concrete method, high-strength steel cables, known as tendons, are placed inside the mould before the concrete is poured. The tendons are then tensioned to compress the concrete, which increases its strength and durability. This method is used to produce large, heavy-duty components, such as beams and columns, for use in bridges and other infrastructure projects.

  1. Autoclaved aerated concrete method

The Autoclaved Aerated Concrete (AAC) method is a type of precast concrete that uses a mixture of cement, lime, sand, and water, combined with a foaming agent. The mixture is poured into a mould and then autoclaved, which cures the product and creates a lightweight, cellular material that has excellent insulation properties. AAC is commonly used for wall and floor panels in residential and commercial buildings.

  1. Vacuum concrete method

In the vacuum concrete method, the concrete mix is placed into a mould that is then sealed and connected to a vacuum pump. The pump creates a vacuum that removes the air from the concrete, allowing it to achieve maximum compaction and density. This method is suitable for the production of precast concrete products that require high strength and durability, such as railway sleepers and bridge components.

In conclusion, precast concrete offers numerous benefits, including faster construction times, improved quality control, and reduced on-site labour costs. The different precast concrete methods, such as wet-cast, dry-cast, precast prestressed concrete, autoclaved aerated concrete, and vacuum concrete, allow to produce a wide variety of components that can be used in a range of construction projects. The method chosen for a project will depend on the specific requirements of the product and the project.

Read more: Precast concrete flooring, panels, stairs and walls

Concrete DNA PRECAST

Do you have a factory that produces precast concrete? We have the solution for you! It helps you to demould sooner and track the progress of the units. In this way, you will know how to improve your production. By knowing the exact time you should demould, you can prevent delays. Concrete DNA PRECAST gives you sensor data and our AI predicts the curing times and calculates the compressive strength of the concrete. Speak to sales if you want to save both time and money.

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