Can humidity affect concrete curing time? - Explained By Converge

April 7, 2023

Concrete is a widely used construction material, known for its versatility and strength. However, one crucial aspect of working with concrete is understanding the factors that can affect its curing time, and how these factors can be managed to ensure optimal results. Among these factors, humidity plays a significant role in the process of curing concrete. In this article, we will discuss how humidity influences concrete curing time. 

Read more: Can you lay concrete in the rain, concreting in hot weather, and what is the best weather to pour concrete?

What is curing?

Curing is a 28 day process that concrete goes through to harden and develop its desired properties, such as strength and durability. Moisture, temperature, and time are the primary factors that influence the curing process, with humidity being a critical aspect of moisture control. 

Concrete gains strength through a chemical reaction called hydration, which involves the binding of water molecules to cement particles. As a result, the presence of water in the concrete mix is essential for the curing process to occur. Moist is necessary for curing concrete.

Does humidity affect the evaporation rate during curing?

The rate at which water evaporates from the concrete surface is directly affected by the relative humidity in the surrounding environment. When the surrounding environment has high humidity, the rate of evaporation is slowed down. 

This reduced evaporation rate is generally beneficial for the curing process, as it allows for a more extended period of hydration, which in turn leads to stronger and more durable concrete.

Conversely, when the surrounding environment has low humidity, the rate of evaporation is increased, and the concrete may lose moisture too rapidly. This rapid moisture loss can lead to inadequate hydration, resulting in weaker concrete with reduced durability and a higher risk of cracking.

Read more: Read up on how to measure concrete temperature, how to protect concrete from rain and underwater concreting.

How to keep the concrete moist

To ensure optimal concrete strength and durability, it is essential to maintain the proper level of moisture during the curing process. This can be done in several ways, including using:

  1. Water sprays 
  2. Fogging systems
  3. By covering the concrete with wet burlap or other moisture-retaining materials
  4. Follow the concrete mixture guidelines to achieve the best curing conditions for that specific mix 

Window with water drops

Factors that impact the curing process

The initial curing period is crucial for concrete, as this is when it gains most of its strength. During this time, it's essential to monitor humidity levels and make adjustments as needed. Factors that can impact the curing process include:

Local climate and weather conditions

The local weather conditions can affect the concrete curing process:

  1. In consistently high humidity areas, adjusting the curing process to account for slower evaporation rates may be necessary, potentially extending curing time for optimal hydration.
  2. In arid or low-humidity environments, implementing additional moisture-retaining techniques is crucial to prevent concrete from drying too quickly.

The use of additives or admixtures

Here are two ways of using additives or admixtures to control the effects of humidity on curing:

  1. Water-reducing admixtures can decrease the amount of water needed in the mix while maintaining workability, allowing for controlled curing in high humidity conditions.
  2. Hydration-controlling admixtures can help regulate the hydration process in low-humidity environments, ensuring enough time for proper curing.

Read more: Learn more about what happens to concrete if it freezes and the long term effects of hot climates and cold climates on concrete.

Frequently asked questions

Does concrete expand with humidity?

Yes, concrete expands with humidity, as the increase in moisture causes the cement paste and aggregates to swell. However, this expansion is usually minimal and may not have a significant impact on the overall structure, depending on the specific conditions and materials used.

Does concrete dry faster in summer or winter?

Concrete dries faster in the summer when it is hot outside. However, that is not necessarily a good thing because the curing process might be interrupted.

Read more: Complete guide to pouring concrete in freezing conditions.

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