What is Hydraulic Cement ? Uses and How to Apply

Where and When to Use Hydraulic Cement

Ceiling leaking water into living room
Hydraulic cement can solve this problem. Michael Blann / Getty Images

Hydraulic Cement is a product used to stop water and leaks in concrete and masonry structures. It is a type of cement, similar to mortar, that sets extremely fast and hardens after it has been mixed with water. Hydraulic cement is used widely in the construction industry sealing structures below grade and in situations where structures can be affected or submerged in water. 

Hydraulic Cement Uses

Hydraulic cement can be used above of below grade, however, it is extremely useful if used in:

  • Swimming Pools
  • Drainage systems
  • Foundations
  • Elevator pits
  • Basement walls
  • Manholes
  • Sealing around concrete and masonry structures
  • Marine applications.
  • Chimneys
  • Cisterns and fountains

The hydraulic cement 10lb pail will cost approximately $15 and it is also available in larger pail sizes.

How to Apply Hydraulic Cement

Hydraulic cement should be applied to surfaces that have been cleaned, free of oil, dirt, grease or any other contaminant that will affect the bonding with the permanent structure. These are the steps for a successful application:

  1. Be sure to remove all loose particles before applying over the surface.
  2. It is recommended to undercut all areas on which the hydraulic cement will be applied. 
  3. The ACI recommends that the area to be worked should be saturated for 24 hours before the hydraulic cement is applied. 
  4. It is important to maintain the temperature of the area between 45°F (7°C) and 90°F (32°C) during initial curing.Preparation should include enlarging small cracks and holes and avoiding V-shaped cuts.
  1. Hydraulic cement shall be blended using a mechanical mixer with rotating blades to ensure a uniform mix.
  2. Pre-wet mixer and remove excess water from it.
  3. Add water following manufacturer's recommendation and then add the dry hydraulic cement mix. Do not add water once it begins to set.
  4. Blend at relatively low speed and be sure to blend only a small amount of cement that can be placed within working time.
  1. Start applying the hydraulic cement at the top of the crack making your way down. Press firmly the paste into place, maintaining the same amount of pressure until the cement begins to harden and the leak is stopped.
  2. Do not blend excess water as this will cause bleeding and segregation.
  3. Do not use any other admixtures or additives.

Hydraulic Cement Pros and Cons

Hydraulic cement will offer some advantages but it also has some downsides as well. Some of its advantages are:

  • Provide durable repairs that will last for long period of times.
  • Sets and hardens fast, normally three minutes after being mixed with water.
  • It is a cost-effective solution
  • Hydraulic cement is very easy to use
  • Hot water will accelerate the setting time and cold water will retard it
  • Can be used on vertical applications
  • It will maintain its strength even if it's submerged in water
  • Will not corrode nor become rusted
  • Hydraulic cement will not shrink
  • It can fixed leaky pipes and basements without having to stop the leaking.
  • It can be painted within one hour of it being applied

But is also has some drawbacks:

  • Once mixed, the hydraulic cement only remains workable for 10 to 15 minutes.
  • Will not work on frozen surfaces or if the temperature will drop dramatically withing 48 hours
  • Avoid using it when temperature is below 40 degrees Fahrenheit

It is important to highlight that if the problem is due to condensation instead of leaking, hydraulic cement will not solve your problem and you will need to use other solutions.

Hydraulic Cement Health and Safety Precautions

Hydraulic cement must be handled very carefully and you must wear necessary PPE before applying. We encourage you to:

  • Avoid breathing the dust.
  • Avoid any contact with eyes or skin.
  • Silica inhaling may cause lung problems, although there is no real evidence silica is a carcinogen.
  • The use of protective clothing: gloves or mask is recommended.