What is the creep of concrete?

The creep of concrete is the slow deformation or movement of the concrete over time when it is subjected to a constant load. It is a time-dependent phenomenon that occurs due to the slow movement of moisture and molecules within the cement paste, causing it to shift and deform over time.

Creep can occur in any type of concrete, but it is particularly relevant in structures that are designed to carry sustained loads over long periods, such as bridges, dams, and high-rise buildings. Over time, the deformation caused by creep can cause the concrete to crack, which can compromise the integrity of the structure.

An easy example of the creep of concrete can be seen in a long, straight bridge supported by concrete pillars. As the weight of the bridge puts a constant load on the concrete pillars, over time, the concrete will slowly deform and shift due to creep. 

This can cause the pillars to crack or bend, which can compromise the integrity of the bridge.

To prevent this from happening, engineers and builders may use high-strength concrete or distribute the load more evenly to reduce the stress on any one area of the concrete.

Creep of concrete duration details

The duration of creep of concrete is a function of several factors, including the magnitude and duration of the applied load, the age of the concrete, the type of cement used, and the environmental conditions to which the concrete is exposed.

Creep in concrete is a time-dependent phenomenon, meaning that the longer the concrete is under sustained load, the greater the amount of deformation that will occur due to creep. However, the creep rate generally decreases over time, meaning that the amount of deformation that occurs in the first few months or years after the concrete is poured will be greater than the amount of deformation that occurs later on.

Factors affecting the creep of concrete

1. Moisture content: The amount of moisture in the concrete can affect creep. High moisture content can increase the rate of creep.
2. Age of concrete: The older the concrete, the more likely it is to creep.
3. Temperature: The temperature of the concrete can affect the rate of creep. High temperatures can increase creep, while low temperatures can decrease it.
4. Type of cement: Different types of cement have different creep rates. For example, concrete made with high-strength cement will generally have a lower creep rate than that made with regular cement.
5. Aggregate type: The type of aggregate used in the concrete can affect its creep rate. For example, concrete made with crushed stone aggregate will generally have a lower creep rate than that made with rounded river gravel.
6. Stress level: The level of stress on the concrete can affect creep. Higher stress levels will generally result in higher creep rates.
7. Humidity: Humidity can affect the rate of creep, with higher humidity generally increases the rate of creep.
8. Duration of loading: The longer the concrete is under load, the more likely it is to creep.
9. Concrete mix design: The specific mix design used can affect the creep rate of concrete. A mix with a higher water-cement ratio will generally have a higher creep rate.

Prevent creep of concrete

1. Use high-strength concrete: High-strength concrete has a lower creep rate than regular concrete and can withstand more sustained loads over time.
2. Reduce the water-cement ratio: Using a lower water-cement ratio in the concrete mix can help reduce the creep rate. This is because a lower water-cement ratio produces denser, stronger concrete that is less susceptible to deformation.
3. Use aggregates with higher strength and stiffness: Using aggregates such as crushed stone that have a higher strength and stiffness can help reduce the creep rate.
4. Use reinforcement: Reinforcing the concrete with steel or other materials can help reduce the amount of deformation that occurs due to creep.

Also read: What is the difference between creep and shrinkage?