Definition - What does Hydraulic Cement mean?
Hydraulic cement is any cement that sets and hardens after being combined with water. Most construction cements are hydraulic. One common application for special hydraulic cement blends is repairing cracks and leaks. Hydraulic cement is used widely in the construction industry for sealing structures below grade and in situations where structures can be affected by or submerged in water.
Hydraulic cement is a non-corrosive, non-rusting and non-shrink substance. It is made of hydraulic calcium silicates, generally containing calcium sulfate.
Corrosionpedia explains Hydraulic Cement
Hydraulic cement is a type of cement, similar to mortar, that sets extremely quickly and hardens after it has been mixed with water. It is made by placing some of the cement in a concrete mix with activated aluminum silicates, pozzolanas, such as fly ash, to activate cement setting in wet conditions, and further protects hardened concrete from chemical attack.
Any dry powdered cement is considered hydraulic because it sets and hardens after being combined with water. The product commercially referred to as "hydraulic cement" is usually a blend of Portland cement with certain additives that greatly decrease the setting time, allowing it to set and cure in wet conditions. These additives also prevent the mix from shrinking like normal cement, and some may actually expand slightly.
Hydraulic cement should be applied over surfaces that have been cleaned, free of oil, dirt, grease or any other contaminant that affects the bonding with the permanent structure. It is recommended to undercut all areas on which the hydraulic cement is to be applied.
Hydraulic cement has advantages such as:
- Provides durable, long-lasting repairs
- Sets and hardens quickly, normally three minutes after being mixed with water
- Very easy to use
- Can be used on vertical applications
- Does not corrode or rust
- Does not shrink
However, once mixed, the hydraulic cement only remains workable for 10 to 15 minutes. It also does not work on frozen surfaces of if the temperature drops dramatically within 48 hours.