Concrete Repair Mortars

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Flexcrete Monomix

A low density, high strength, shrinkage compensated, waterproof mortar for the structural repair, rendering and profiling of vertical, horizontal and overhead surfaces.

Class R3 General Purpose Structural Repair Mortar

Product Description:

MONOMIX is a low density, high strength, shrinkage compensated, waterproof mortar for the structural repair, rendering and profiling of vertical, horizontal and overhead surfaces.

  • Incorporates the latest proven cement chemistry, microsilica, fibre and styrene acrylic copolymer technology.
  • Pre-packaged material requiring mixing with clean water on-site to give an easily trowellable mortar with maximum application thickness of 80mm in vertical, horizontal and overhead situations.
  • High bond strength exceeds tensile strength of concrete, thus ensuring monolithic performance of the repair.
  • Dense matrix offers low permeability to water, even at 10 bar pressure, and very high diffusion resistance to acid gases and chloride ions. • Improved tensile and impact strength. Excellent low sag properties.
  • Non-toxic when cured and is listed as authorised under Regulation 31 for use in the supply of drinking water.
  • Economic mortar generally requiring no substrate or inter-layer priming. Part bags can be mixed.
  • Easily overcoated with specialist membranes to provide further protection and aesthetic quality.

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. Approved by the BBA, Certificate No. 05/4276. Listed under DWI Regulation 31 for drinking water applications.

MONOMIX is a single component cementitious mortar which incorporates the most advanced cement chemistry, microsilica, fibre and styrene acrylic copolymer technology. This results in a rapid hardening, low density, high strength mortar with enhanced polymer properties. The thixotropic nature of the product enables easy high build trowel application for the structural repair of voids and the rendering and re-profiling of both vertical, horizontal and overhead surfaces. The product is supplied as a single component system ready for on-site mixing and use, requiring only the addition of clean water.

Technical Data:

Mixed colour concrete grey
Mixed density 1725 kg/m³ at 0.14 water : powder ratio
Min application thickness     
Max application thickness     
80mm per layer
Min application temperature     
Max applicatoin temperature    
Working life (approx) 60 minutes at 20°C 
30 minutes at 40°C

Mechanical Characteristics (Typical) :

Compressive Strength: BS 4551 Tested at 20°C 1 day 23.5 MPa 7 days 41.0 MPa 28 days 48.0 MPa Water Permeability Coefficient: Taywood Test by Penetration: 9.65 x 10-15 m/sec ie. 5.7mm of MONOMIX = 1000mm of typical concrete Oxygen Diffusion Coefficient: Taywood Test: DO2 = 2.72 x 10-4 cm2/sec (Normal concrete: DO2 = 2.12 x 10-3 cm2/sec) Electrical Resistivity: 4-Point Wenner Probe: 10,000 Ω/cm Suitable for use in conjunction with CP Systems


Mechanically remove all damaged concrete back to a sound core. Wherever possible, the full circumference of the steel reinforcement should be exposed to at least 25mm behind the bars and 50mm beyond the point at which corrosion is visible. On cutting back, feather edges must be avoided. The perimeter of the repair area should be stepped to a depth of 10mm by means of saw, disc cutting or preferably using a power chisel. The areas to be repaired must be free from all unsound material, i.e. dust, oil, grease, corrosion by-products and organic growth. Smooth surfaces should be roughened, all loose material and surface laitance removed, and reinforcement cleaned to bright steel using wet grit blasting techniques or equivalent approved methods. The strength of the concrete subbase should be a minimum of 20 MPa. The prepared substrate should be thoroughly soaked with clean water until uniformly saturated without any standing water.

MONOMIX 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.


MONOMIX 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 between 3.3-3.7 litres of clean water per 25kg bag depending upon the desired consistency. For part bags, this equates to 5.0-6.0 volumes of powder to one volume of water. Typically, for high build applications, use 3.5 litres of clean water per bag which gives a water : powder ratio of 14%. Normal mixing time depends on the type of mixer used, 2-3 minutes is average. Mix so as to entrain as little air as possible. Use without delay.


MONOMIX can be applied by float or trowel as a render, resulting in application thicknesses of 80mm, even in soffit situations. If necessary, support with shuttering to allow for compaction if working to reveals, etc. The application thickness achievable is dependent upon the substrate and care must be taken to ensure that an initial thickness of mortar, typically 5-10mm, is well placed and adhered before building up to larger depths.

For repairs which require multi-layer applications, it is important to ensure that previous layers are well keyed and stable but not fully set prior to the application of subsequent layers. No inter-layer priming is required. Final profiling of a high quality is easily achieved with a steel float.

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: 16.5 litres per 25kg pack
Coverage: A 25kg pack covers 1.65m² 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.

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12 Fenlake Business Centre, Fengate, PE1 5BQ

01733 560362

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