Concrete Repair Mortars

Flexcrete Fastfill

Protective coating for exposed concrete.

Class R4 Rapid Setting Structural Repair Mortar

FASTFILL is a rapid setting, Portland cement-based structural mortar for the durable repair of concrete which cannot be taken out of service for long periods, or in areas subjected to heavy wear such as roads, runways, bridges, decks, floors and footpaths. Can be used as supplied or bulked out with sharp sand or aggregate.


  • Incorporates the latest proven cement chemistry, fibre and styrene acrylic copolymer technology.
  • Reliable strength development, even at low temperature, gives rapid return to service.
  • Pre-packaged material requiring mixing with clean water. Can be bulked out with sand or aggregate.
  • High bond strength exceeds tensile strength of concrete, thus ensuring monolithic performance of the repair.
  • Sets in 10 minutes at 20°C yielding a durable, high strength mortar.
  • Dense matrix resists 10 bar water pressure. Very high diffusion resistance to acid gases and chloride ions.
  • Sulphate resistance to class DS-5/5m of BRE Special Digest 1 and ideally suited for sewage and wastewater
  • Portland cement base with physical properties of cured material similar to base concrete.
  • Non-toxic when cured and is listed as authorised under Regulation 31 for use in the supply of drinking water.
  • Economic mortar requiring no substrate or inter-layer priming. Part bags can be mixed.
  • CE marked in accordance with BS EN 1504 Part 3. Fully complies with the Highways Agency Standard BD 27/86 for the repair of Highway Structures. Authorised under Regulation 31 for use in the supply of drinking water.

Technical Data:

Mixed colour     concrete grey
Mixed density     2150 kg/m³
Min application thickness     5mm
Max application thickness     

50mm on vertical & soffits
100mm on decks & floors
300mm when bulked out
Min application temperature     5°C
Max applicatoin temperature     40°C
Working life (approx)     10 minutes at 20°C

FASTFILL is a single component, polymer modified, fibre-reinforced, Portland cement based repair compound, which is physically and chemically compatible with the host concrete. It exhibits unique hydraulic properties to produce a rapid curing mortar with enhanced polymeric properties and reliable strength development which is not significantly affected by low temperature use. Can be used as supplied up to 100mm deep, or can be bulked out with sharp sand or aggregate to a flowing consistency for floor or deck repairs up to maximum depth of 300mm.

FASTFILL is highly polymer modified and as a result concrete surfaces do not generally require a primer. Highly porous substrates should be primed with BONDING BRIDGE 842. Two coats of STEEL REINFORCEMENT PROTECTOR 841 should be applied to the prepared steel by brush. For further information, please refer to relevant data sheets.

FASTFILL should be mechanically mixed using a forced action pan mixer or in a clean drum using a drill and paddle. A normal concrete mixer is NOT suitable.

For normal applications, use 3.5 litres of clean water per 25kg bag depending upon the desired consistency. For part bags, this equates to 5.5 volumes of powder to one volume of water. For screeding applications or larger pockets in decks up to a maximum depth of 100mm, a clean, washed, Medium Grade concreting sand can be introduced, up to 50% by weight.

For deep repairs up to a maximum of 300mm in a single application, or where a pourable concrete is required, coarse, clean aggregates (5 -10mm size) can be introduced into the mix, in up to equal proportions by weight, without adversely affecting its physical performance.
For normal applications, FASTFILL should be compacted, using a placing technique to remove entrapped air, in layers not exceeding 50mm in vertical or soffit situations, or 100mm deep in pockets. When bulking out to the maximum of 300mm, support with shuttering and compact to remove entrapped air. For repairs which require multi-layer applications, it is important to ensure that the previous layers are well keyed and stable but not fully set (usually 15-30 minutes dependent upon temperature) prior to the application of subsequent layers. Final profiling of a high quality is achieved with a steel float.

When applying material to floors, the area should be divided up and each bay completed within the working life of the FASTFILL. Typically bay sizes should be restricted to 1m2 but please consult our Technical Department for further advice. Do not polish the surface with a steel float, but use a stiff brush on the wet surface to provide a slip-resistant finish.

Normal concreting procedures should be strictly adhered to. It is important that the surface of the mortar is protected from strong sunlight and drying winds with FLEXCRETE CURING MEMBRANE WB, polythene sheeting, damp hessian or similar.

All tools should be cleaned with water immediately after use.

12 months in dry, frost free conditions with unopened bags at 20°C.
Pack Size: 25kg
Yield: 13.3 litres per 25kg pack. Up to 23 litres when bulked out with aggregate
Coverage: A 25kg pack as supplied covers 1.33m² at 10mm thickness
Safety Data Sheet available on request.

The information herein is correct to the best of our knowledge, but it does not necessarily refer to the particular requirements of the customer. If the customer has any particular requirements it should make them known in writing to Flexcrete Technologies Limited, and obtain further advice accordingly.

back to Concrete Repair Mortars

12 Fenlake Business Centre, Fengate, Peterborough , PE1 5BQ

01733 560362

sales@concreterenovations.co.uk

Follow Us