Cemgrout UW


Cemix® Cemgrout UW is an underwater, high strength, waterproof, structural cementitious grout. Characteristics include minimal washout, waterproof, high strength, shrinkage compensation, excellent chloride ion resistance & durability.

Typical Application / Uses:

Cemix® Cemgrout UW may be used for:

  • All underwater grouting applications.
  • Marine pile repairs & encapsulation.
  • Anchors, bolts, starters & dowels underwater.


  • Minimal washout underwater.
  • Waterproof.
  • Pourable or pumpable.
  • One component.
  • High strength.
  • Shrinkage compensated.
  • Durable.
  • Impermeable to water borne aggressors such as chloride ions.
  • Improved abrasion resistance.


Durability Enhancer, Steel Protection & Waterproofing:

Cemgrout UW is enhanced with Cemix® Penetron Admix. This admixture is an integral crystalline concrete durability enhancer & waterproofing material, which further protects & waterproofs the mortar in-depth by making it completely impermeable to water borne aggressors such as chloride ions. This admixture permanently waterproofs & protects the grout & imbedded structural steel from long-term corrosion & deterioration.

Substrate Preparation:

Substrates should be clean & free from all contaminants, loose particles, coatings, curing compounds, dirt, mould, oil etc. Substrates must be sound, rough and dampened to ensure a good bond.

Formwork Preparation:

When grouting around marine piles, they must be enclosed with good quality rigid watertight formwork. The formwork must be able to rigidly confine the Cemgrout UW until it has set.


Mix whole bags of product. Mix thoroughly for 2 to 3 minutes using a drill & paddle or suitable mechanical grout mixer. If a less fluid consistency is required, less water can be added. More water will increase flow but reduce strengths. Add 4L of water to the mixer & then add the product to the water. Add rest of water slowly whilst mixing until the desired consistency is achieved. Typical total water for a pourable consistency is approximately 4.5L per 20kg bag. Use product immediately. This is a reasonably fast setting product; do not mix more product than can be mixed, placed & finished in 40 minutes. Use chilled water in hot weather as well as to extend working time slightly in normal ambient temperatures. Use chilled mixing water for deep or larger volume pours.


Cemgrout UW may be poured by tremie or pumped into place. The pump or tremie should fill from the bottom up displacing the water out the top. Compact as required. Immediately trowel finish as required.


Cure product above the waterline thoroughly after it has set by keeping it wet & covered for at least 3 days. Avoid product freezing for at least 3 days.

Technical Data:

Appearance – Sand/Cement grey powder.

Strength (MPa) – 40MPa at 7 days; 60MPa at 28 days; 4.5L of water.

Application Temp – 1˚C - 25˚C

Yield / Coverage – 12.1L or 0.0121m3 per 20kg bag at 4.5L of water.

Bond Strength – >3MPa

Thermal Coeff. Of Exp – 9.0 x 10-6 mm/mm/˚C

Chloride Ion Permeability – >1000 coulombs

Working Time – 40 minutes at 20˚C

The data shown above reflects typical results based on laboratory testing under controlled conditions. Reasonable variations may occur on site.


Do not apply product onto surfaces less than 1OC and more than 25OC.


  • Large/deep volumes of grout can generate excessive heat whilst hardening. This may lead to thermal cracking.
  • In very hot water, use chilled mixing water.
  • In very cold weather, use warm mixing water.
  • More mixing water will increase flow but reduce strengths.


Clean all tools with water & brush immediately after use.


Can be stored in its original packaging in a dry place well sealed for a period of 6 months after production. Do not store opened bags.

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