Rapid Repair F


Cemix® Rapid Repair F is a super high early strength flowable structural performance concrete for concrete repairs & concreting which are poured into place. It is useful when a flowable product is required, reinforcing is congested and/or repair volumes are too large for hand placed mortars. It is used for remedial work & concreting where super high early strengths are required.

Typical Application / Uses:

Cemix® Rapid Repair F may be used for:

  • Flowable concrete repairs & performance concreting to all concrete structures requiring super high early strength & minimal downtime.
  • Cold weather repairs & concreting.
  • Early traffic & overcoating applications.
  • Congested steel reinforcing repairs & concreting.
  • Smooth off form finishes.
  • Columns & beams.
  • Bridges.
  • Marine structures.
  • Water retaining structures.
  • Precast connections and between precast elements.
  • Structural void filling.


  • Super high early strength.
  • Trafficable in 6 hours.
  • Can be over coated in 6 hours.
  • Flowable.
  • 5mm max aggregate size.
  • One component.
  • Shrinkage compensated.
  • Short curing times.
  • High bond strength.
  • Durable.
  • Waterproof.
  • Impermeable to water borne aggressors such as chloride ions.
  • Improved abrasion resistance.


Durability enhancer, steel protection & waterproofing:

Cemix® Rapid Repair F contains 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 protects the mortar & imbedded structural steel from long-term corrosion & deterioration.

Substrate Preparation:

Concrete substrates should be sound & roughened to ensure a good bond. They should be uncoated & clean, free from all contaminants, loose particles, dirt, oil, mould, curing compounds, sealers & paints etc. For a durable repair, cut a square or rectangular perimeter edge around the repair at least 25mm in depth. Remove all oxidation from exposed rebar & ensure that there is at least 25mm (or ‘finger room’) behind each rebar. For deep critical repairs use anchors and steel mesh as required to enhance bonding.The better the substrate preparation & condition the better the end result. The concrete substrate should ideally be at least 3 months old.

Formwork Preparation:

The area to be repaired must be enclosed with good quality rigid watertight formwork. The formwork must be able to rigidly confine the Cemix® Rapid Repair F until it has set. Treat the formwork with a Cemix form release agent. Formwork should be flushed out just prior to application.

Header Box & Air Vents:

Where appropriate, use a suitable header box delivery system to pour the product into place. Create a head of pressure to force the product into place. Avoid air entrapment by use of filling pipes or tremies, which fill from the bottom up. Use suitable air vents to vent air as the product flows into place.

Movement / Control Joints:

Honour any control joints in the concrete substrate – do not apply product over control joints.


Mix whole bags of product. Add 2.5L of water to mixer & then add product to water. Add rest of water slowly whilst mixing until the desired consistency is achieved. Maximum total water is approximately 3L per 20kg bag. Mix thoroughly for 2 - 3 minutes using a drill & paddle or mechanical mortar mixer. Use the product immediately. This is a fast setting product; do not mix more product than can be mixed, placed & finished in 30 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 large volume pours.


Saturate the concrete substrate with water just prior to concrete application. Avoid water ponding. Pour the Cemix® Rapid Repair F into place while the substrate is still damp. Where appropriate, use a suitable header box & pipe or tremie delivery system. Application is from the bottom of the repair up, completely filling the void & avoiding air entrapment. Compact the concrete once it is in place. For a durable repair apply product to a minimum depth of 25mm. Immediately trowel finish as required.


Cure product thoroughly after it has set by keeping it wet & covered for at least 6 to 24hrs. Avoid product freezing for at least 6hrs.

Technical Data:

Appearance – Sand/Cement grey powder.

Strength (MPa) - 40MPa @ 6hrs; 50MPa @ 30hrs; 60MPa @ 28 days

Application Temp- 1ºC - 25ºC

Yield / Coverage - Approximately 10.6L or 0.0106m3 per 20kg bag.

Bond Strength – > 3MPa

Thermal Coeff. of Exp – 9.0 x 10-6 mm/mm/ ºC

Chloride Ion Permeability – < 1000 coulombs

Working Time – 30 minutes @ 20ºC

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


  • For deep & large volume pours, use chilled mixing water to counteract the heat of hydration and prevent thermal cracking or seek technical advice.
  • This is a fast setting product with limited working time. Use chilled water to extend working time slightly or seek technical advice.
  • Do not apply product onto surfaces less than 1ºC & more than 25º C.
  • Do not use product in temperatures less than 1ºC & more than 25º C.
  • In applications where surface aesthetics is important, seal finished surface with Cemix® Cemprotect or Cemix® Cemprotect WO 24 hours after installation.


Clean all tools with water & brush immediately after use.


This product can be stored in its original packaging in a dry place well sealed for six (6) months after production. Do not store opened bags.

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