What is the Difference Between Hydraulic and Non Hydraulic Cement

Cement is a binder used in construction to hold materials together and provide structural integrity. There are two main types of cement: hydraulic and non-hydraulic. Each type has its own specific applications depending on the project’s environment and requirements.

What is the difference between hydraulic and non hydraulic cement? Hydraulic cement hardens due to a chemical reaction with water whereas, non hydraulic cement hardens through a process called carbonation, which is a reaction with carbon dioxide in the air.

Key Areas Covered

1. What is Hydraulic Cement
      – Definition, Features
2. What is Non Hydraulic Cement
      – Definition, Features
3. Similarities Between Hydraulic and Non Hydraulic Cement
      – Outline of Common Features
4. Difference Between Hydraulic and Non Hydraulic Cement
      – Comparison of Key Differences
5. FAQ: Hydraulic and Non Hydraulic Cement
      – Answers to Frequently Asked Questions

Key Terms

Hydraulic Cement, Non Hydraulic Cement, Cement

What is Hydraulic Cement

Hydraulic cement is made up of limestone, clay, and gypsum ground into a fine powder. Modern hydraulic cement may sometimes include additional ingredients to improve the setting time and other properties. One example of this is Portland cement.

Hydraulic cement is effective for waterproofing materials and helps to patch fountains, pools, and cisterns and line the bottom of ponds. Another feature of hydraulic cement is its rapid hardening, making it useful for quick fixes. Cracked sidewalks, chipped concrete, or leaky basements can all be addressed with hydraulic cement. Due to its water resistance and durability, hydraulic cement is well-suited for constructing dams, docks, and other structures exposed to water or harsh environments. Anchoring bolts, grouting electrical conduits, and even creating fire-resistant linings are other uses of hydraulic cement.

To apply hydraulic cement, you mix the powder with water to create a paste, then spread it onto the desired area. For a successful application, follow the manufacturer’s instructions on mixing ratios and setting times.

What is Non Hydraulic Cement

Non hydraulic cement needs carbon dioxide for setting, unlike hydraulic cement, which needs water to set. This means they require dry conditions and exposure to air for the hardening process, called carbonation, to occur. Common examples include lime, gypsum plaster, and oxychloride cement.

Non hydraulic cement also has some limitations, such as its dependency on carbon dioxide and dry weather for the setting process. This is an obstacle faced by the industry, especially when it comes to outdoor construction. When compared to hydraulic cement, this cement generally sets slower and achieves lower strength.

However, lime plaster, for instance, is known for its breathability and aesthetics, making it ideal for historical restorations and interior decorative finishes. Gypsum plaster offers fire resistance and helps to create smooth surfaces on walls and ceilings.

Similarities Between Hydraulic and Non Hydraulic Cement

1. Both types of cement act as binders.
2. Although the specific compositions differ, both types share some basic ingredients.

Difference Between Hydraulic and Non Hydraulic Cement

Definition

• Hydraulic cement is a type of cement that hardens through a chemical reaction with water, a process called hydration. Hydraulic cement, on the other hand, is a type of cement that relies on carbon dioxide (CO₂) in the air for a process called carbonation to harden.

Hardening

• Hydraulic cement hardens with water and is perfect for projects exposed to moisture, while non hydraulic cement hardens in the presence of dry air (carbon dioxide).

Hardening Time

• Hydraulic cement generally sets and hardens much faster than non-hydraulic cement.

Strength

• Hydraulic cement generally achieves a higher overall strength compared to non hydraulic cement.

Conclusion

In conclusion, the difference between hydraulic and non hydraulic cement lies in their hardening mechanisms: hydraulic cement relies on hydration with water, while non-hydraulic cement undergoes carbonation with dry air.

FAQ: Hydraulic and Non Hydraulic Cement

1. Which is better, hydraulic or non-hydraulic cement?

Hydraulic cement is more durable than non-hydraulic cement and can be used in wet or dry conditions. It is also resistant to chemicals and heat. It can be applied even underwater.

2. When not to use hydraulic cement?

Hydraulic cement is not suitable for repairing concrete cracks, waterproofing joints and seams, or patching holes in areas where flexibility is needed because it hardens quickly and is rigid once set. This lack of flexibility can cause further damage over time as the surrounding materials expand and contract due to temperature changes or ground movement.

3. What is the advantage of non-hydraulic cement?

Non-hydraulic cement does not require water to harden. It will not set in the presence of wet conditions. It only sets in dry air with carbon dioxide.

4. What are the substances needed to produce non-hydraulic cement?

Lime, gypsum plasters, and oxychloride are the required raw materials to produce non-hydraulic cement.

5. Why is it called hydraulic cement?

Hydraulic cement is called so because it requires water to set. In the presence of water, certain chemical reactions happen in order to make the cement set.

Reference:

1. “Hydraulic Cement.” Science Direct.
2. “Cement.” Wikipedia. Wikipedia Foundation.

Image Courtesy:

1. “Labourers mixing Cement” By Iniabasi Udosen – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Cement Wall Texture” (CC0) via NeedPix