Flexcrete Cementitious Coating 851 is a thixotropic, polymer modified, cementitious waterproofing coating for internal or external structural waterproofing of concrete and other mineral substrates. It cures to form a hard, durable, highly alkaline coating with a degree of flexibility. It provides economic reinstatement of concrete cover to ensure the design life is achieved and to extend the service life of existing structures. It imparts a high level of protection from chloride ingress on highway and coastal structures.

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• Preparation
• Mixing
• Application
• Application Top Tips
• Technical Data

Preparation

The areas to be repaired must be free from all unsound material including laitance dust, oil, grease, corrosion byproducts and organic growth. Smooth surfaces should be roughened.

Any defective concrete should be reinstated with the appropriate Flexcrete repair mortar.

The compressive strength of the parent concrete should be minimum 20 MPa.

The prepared substrate should be thoroughly soaked (preferably 24 hours before) with clean water until uniformly saturated without standing water.

Substrate Priming:

Cementitious Coating 851 does not generally require a primer. On potable water structures, roofs and decks are sealed with a polymer admixture diluted with clean water.

Mixing

Cementitious Coating 851 is supplied as a two pack, Part A liquid and Part B powder. The two components must not be split. Mix all of Part A with all of Part B.

Shake Part A (liquid) and pour into a suitable mixing vessel. Slowly add the Part B (powder) and mix for a minimum of 5 minutes until homogenous, without any lumps. Mix with a slow-speed drill and paddle designed to entrap as little air as possible.

Note - These instructions must be adhered to as the manufacturer will not be responsible for failure due to incorrect mixing.

Application

Cementitious Coating 851 is applied using brush, trowel or spray techniques. Care should be taken to ensure that air is not entrapped onto the surface.

For vertical and overhead use, apply in two 1mm coats, applying the second coat when the first coat is stable but not fully set (typically 30-90 minutes).

On roofs or decks, apply in a single 2mm layer, spreading with a notched trowel, squeegee or skid leveller, and immediately use a spiked roller to remove entrapped air.

Detail Work:

Where movement is anticipated around penetrations and over joints or cracks, apply a 1mm thick stripe coat of Cementitious Coating by brush and immediately embed suitable tape. Allow to stabilise before proceeding with the main application.

Application Top Tips

• Regularly check the coating thickness during application using a wet film thickness gauge
• Apply Cure-Seal WB as an even fine mist spray. Do not over apply or allow to pond on the surface or cracking may occur
• Cementitious Coating 851 is not a decorative coating. It can be overcoated with Flexcrete membranes to give a coloured finish.
• For light to moderate traffic, seal sanded surfaces with Cure-Seal WB
• Please consult our Technical Department when waterproofing underneath road asphalt
• In cold, humid conditions, condensation may form on freshly coated surfaces resulting in darkening of the finish and retardation of set
• Cold Weather Working - Do not use any Part A which has been frozen. When applying to potable water structures the minimum application temperature is 7°C
• Hot Weather Working - Store material in cool conditions to maximise working life. Shade applied material from strong sunlight. If possible, avoid extreme temperatures by working at night

Technical Data