Methods of Steam Curing of Concrete

Methods of Steam Curing of Concrete and its Advantages

Concrete is an extremely ubiquitous material and is used heavily in all types of modern construction projects. It is a composite material (admixtures) which is made by mixing cement, water, and aggregates in varying proportions to enhance some specific properties. Concrete has been a vital component of construction for centuries.

The incredible durability, strength, and versatility of concrete make it an essential part of various applications. However, the curing process of concrete determines how it achieves the desired properties.

These inherent properties of concrete can be actively optimized through different methods. Steam curing is one such method. It is a technique that accelerates the strength gaining phase of concrete.

In this article, you will learn everything you need to know about steam curing of concrete, such as its definition, working process, methods of processing, advantages, disadvantages, and applications.

What is steam curing of concrete?

Steam curing of concrete is a process where the concrete is exposed to steam at atmospheric or high pressures. This accelerates the hydration of cement and speeds up the strength gain while reducing the curing time.

This method is particularly helpful in processes where rapid turnover of molds is essential for efficiency, such as in precast concrete production.

How does steam curing work?

The hydration of cement is the chemical reaction between cement and water which is crucial to the curing process. This reaction produces calcium silicate hydrate (C-S-H) and calcium hydroxide. These compounds contribute to the strength and durability of concrete. Under normal conditions, this reaction is relatively slow and may take days or weeks to complete.

However, steam curing accelerates this process by providing additional heat and moisture. The increased temperature from the steam enhances the rate of hydration, while the moisture ensures that the reaction has sufficient water.

The steam curing process for concrete can be broken down into several stages –

1. Pre-steaming

In the first stage, the concrete is allowed to hydrate naturally for a short period, which is usually a few hours, after casting. This treatment of concrete helps prevents cracking and thermal shock.

2. Heating

Next, steam is used to gradually increase the temperature. Rapid heating should be avoided to prevent thermal gradients and potential cracking.

3. Constant temperature

The concrete is kept at a constantly high temperature, typically between 60° C and 90° C for several hours. This step is crucial for rapid strength gain.

4. Cooling

The temperature of the compound is then gradually decreased till it reaches ambient conditions. This slowed cooling prevents thermal stress and cracking in the concrete.

What are the different methods of steam curing concrete?

There are two main methods of steam curing concrete –

Autoclaving / High-pressure steam curing

The autoclaving method involves curing concrete at high pressures and temperatures. This is usually done at around 180° C and at pressures of up to 1.2 MPa, in an autoclave.

The high-pressure steam noticeably accelerates the hydration process which results in extremely high early strength. Autoclaving is used for specialized concrete products like autoclaved aerated concrete (AAC) blocks. These are lightweight construction blocks and have excellent thermal insulation properties.

AAC Industry Chemicals: The chemicals use to manufacture AAC bricks

Atmospheric pressure steam curing

In this concrete steam curing method, steam is applied at atmospheric pressure. It is widely used in the production of precast concrete components.

The concrete ingredients are kept in a chamber where steam is constantly blown over it. This method is relatively simple and cost-effective which makes it suitable for various applications in the construction industry.

What are the advantages and benefits of steam curing concrete?

The steam curing of concrete offers several advantages which make it a preferred method in various construction scenarios.

These are some of the express benefits and exceptional advantages of steam curing concrete –

Quicker strength gain

One of the biggest benefits of steam curing concrete is the accelerated strength development. This rapid strength gain permits quicker removal of formworks and faster turnaround times in precast concrete production. As a result, it enhances overall productivity of production of precast components.

Enhanced early age strength

Steam curing significantly boosts the early age strength of concrete. This early strength gain is crucial for projects with strict construction schedules. This strength enhancement allows for quicker production, transportation, and installation of concrete elements.

Better control over curing conditions

By using controlled steam environments, the curing factors like temperature and humidity can be precisely controlled. This control ensures uniform curing and reduces the risk of defects caused by uneven curing.

Enhanced durability

Steam curing can also improve the long-term durability of concrete by promoting a more complete hydration process. The dense microstructure developed from accelerated curing can improve the concrete’s resistance to weathering and chemical attacks.

Energy efficiency

In some cases, steam curing can be more energy-efficient than other forms of thermal treatments. For instance, using waste heat from industrial processes for steam generation can decrease overall energy consumption and help make the production process more efficient in terms of energy and resources.

Are there any disadvantages of steam curing of concrete?

Despite its numerous benefits, steam curing of concrete has some drawbacks that must be considered –

Initial cost

Setting up steam curing facilities, especially for autoclaving (high-pressure steam curing), requires significant initial investment in equipment and infrastructure. This cost can be a barrier for small-scale operations.

Complex process

The steam curing process requires having complete control over temperature and humidity. This can only be achieved by hiring skilled operators and using precise monitoring systems. Any deviation from the optimal conditions can cause defects in the concrete, and lead to unsatisfactory outcomes.

Thermal cracking risk

Rapid changes in temperature during the heating and cooling phases can cause thermal stress and create cracks in the concrete. Hence, proper control over the temperature and careful gradual heating/cooling are essential to prevent these problems.

Higher energy consumption

The steam curing method can be energy-efficient, but it still requires a substantial amount of energy to generate the volume of steam required to complete the process effectively. This energy consumption can be a concern in areas with high energy costs or limited energy resources.

What are the applications of steam-cured concrete?

The accelerated curing process and enhanced properties of steam-cured concrete make it suitable for various applications, such as –

Precast concrete production

Steam curing is commonly used in the production of precast concrete elements like beams, columns, slabs, and pipes. The rapid early strength gain allows for quick mold turnover which helps in increasing the efficiency of the production process.

Prestressed concrete

Prestressed concrete elements are subjected to high tensile stresses. They also benefit from the early strength gain provided by the steam curing method. This early strength is vital for applying prestress and handling the products.

Autoclaved Aerated Concrete (AAC)

High-pressure steam curing (autoclaving) is also used to produce AAC blocks and panels. These are lightweight concrete products that offer excellent thermal insulation. AAC components are widely used in modern building construction.

Bridge construction

Steam curing can also be used to construct bridge components, where early strength and durability are critical. Precast bridge segments, decks, and girders can be quickly produced and installed.

Concrete pipes

The production process of concrete pipes often uses the steam curing method to achieve the necessary strength and durability for various infrastructure projects. These products are widely used in water supply networks and sewage systems.

Architectural precast concrete

Additionally, the steam curing technique is used to produce architectural precast elements with intricate designs and finishes. The quick curing process ensures that these elements fulfill the expected aesthetic and structural standards sufficiently.


Steam curing of concrete is a reliable technique that significantly enhances the curing process. This helps to give the concrete element not only rapid strength gain but also improved durability. By controlling the temperature and humidity the technique ensures uniform and complete hydration of cement. This helps the concrete to enhance the inherent properties of the concrete.

Despite its initial cost and complexity, the benefits of steam curing, particularly in precast and specialized concrete applications, make it an invaluable method in modern construction. As technology advances and energy-efficient methods evolve, steam curing will continue to play a crucial role in the production of high-quality concrete products.

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