Flexcrete Fastfill is a single component, polymer modified, fibre reinforced Portland cement-based repair mortar. It is rapid curing with enhanced polymeric properties and reliable strength development. Used for the durable repair of concrete subject to heavy wear such as roads, runways, bridges, decks, floors and footpaths. Also suitable for marine repairs and approved for potable water applications.

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• Features & Benefits
• Preparation
• Mixing
• Application & Curing
• Application Top Tips
• Technical Data

Features & Benefits

• Dense matrix with low permeability to water
• High diffusion resistance to acid gases & chloride ions
• Resistant to sulphates to class DS-5M of BRE Special Digest 1
• UKCA & CE marked in accordance with EN 1504-3
• BBA Approved, Certificate No. 05/4276
• Listed under Regulation 31 - England and Wales: Regulation 33 - Scotland: Regulation 30 - NI: for use with potable water
• Highways Standard Series 5700 (Concrete Repairs) and CS 462 (Repair & Management of Deteriorated Concrete Structures)
• Compliant with LU Standard 1-085 ‘Fire Safety Performance of Materials'

Preparation

Mechanically remove all damaged concrete or failed repairs back to a sound core. Except in new construction, expose the full circumference of the steel reinforcement 25mm behind the bars and 50mm beyond visible corrosion.

On cutting back, feather edges must be avoided. Step the perimeter of the repair to a depth of 10mm preferably using a power chisel or by saw or disc cutting.

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 and reinforcement cleaned to bright steel using wet grit blasting techniques or equivalent approved methods. Power tools such as a needle gun, angle grinder or wire brush may be used on concrete which is not chloride contaminated.

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

The prepared substrate should be thoroughly soaked with clean water until uniformly saturated without any standing water. In winter, use warm water or a heat source to ensure the substrate temperature is ≥ 5ºC before application.

Treatment of Steel Reinforcement:

Treat exposed steel reinforcement with 2 x 1mm coats of Steel Reinforcement Protector 841 applied by brush.

Priming of Concrete:

Fastfill does not generally require a primer. Highly porous substrates may be primed with a polymer admixture slurry coat. The slurry coat should also be used when treating larger areas of waterproof concrete.

Mixing

Fastfill should be mechanically mixed using a forced action pan mixer or in a clean drum using a slow speed drill and paddle. A normal concrete mixer is not suitable.

For normal applications, use 3.5 litres of clean water per 25kg bag. For part bags, this equates to 5.5 volumes of powder to 1 volume of water. In cold temperatures, tepid water may be used to adjust working life. Mix for 2-3 minutes entraining as little air as possible. Use without delay.

For screeding applications or larger pockets in decks up to a maximum depth of 100mm a clean, washed, medium grade concreting sand can be added (up to 50% by weight). For deeper repairs, clean sharp 5-10mm aggregate can be added to a maximum of 100% by weight to a produce a semi-pourable consistency

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

Application & Curing

For normal applications, Fastfill should be compacted, using a placing technique to ensure full contact with the substrate. When bulking out with aggregate, temporary support with shuttering may be required. Tamp to remove any entrapped air.

For multi-layer applications, it is important to ensure that the previous layers are well keyed and stable but not fully set (typically 15-30 minutes) prior to the application of subsequent layers. No inter-layer priming is required. Final profiling is achieved with a steel float.

On larger floor repairs, the area should be divided into individual bays of approximately 1m2 to allow for completion of work within the open time. Do not polish the surface with a steel float, use a stiff brush on the wet surface to provide a slip-resistant finish.

In tidal works, allow a minimum cure time of 30 minutes prior to immersion.

All tools should be cleaned with water immediately after use. Materials can be stored for 12 months in dry, frost free conditions with unopened bags at +20°C.

Curing:

Normal concreting procedures must be adhered to. Protect from strong sunlight and drying winds with Cure-Seal WB, polythene sheeting, damp hessian or similar.

Application Top Tips

• When bulking out, base the initial quantity of water on the amount of Fastfill in the mix. Add the minimum amount of extra water to achieve the desired consistency. Do not exceed 4.5 litres per 25kg
• Take care if using very cold mixing water as this will accelerate setting of Fastfill
• DO NOT WET OUT OR PRIME between layers
• DO NOT OVER TROWEL. If the mortar begins to slump, allow to stabilise and refinish
• When finishing, trowel from centre out towards the perimeter working into the edges of the repair
• Consider using a hand-held pointing gun for reinstating mortar joints
• Due to the rapid set of Fastfill, only mix as much material to use within the working life of the mortar
• Do not hand mix smaller volumes
• For large floor repairs, divide into bays and adopt a checkerboard pattern limiting individual bay sizes to a maximum of 1m²
• Fastfill is particularly suited to repairs at temperatures as low as -10°C, but should not be applied to frozen substrates. In cold temperatures use tepid water to adjust working life. Very cold water will shorten working life and accelerate set
• Hot Weather Working - Store material in cool conditions to maximise working life. Shade applied material from strong sunlight. Spray apply a second mist coat of Cure-Seal WB. If possible, avoid extreme temperatures by working at night

Technical Data