Class R4 High Strength Structural Repair Mortar (EN1504-3)


Monomix HD is a high strength, waterproof, shrinkage compensated, standard density mortar with good abrasion resistance for the structural repair, rendering and profiling of vertical, overhead and horizontal surfaces including trafficked areas.

Monomix HD is a single component cementitious repair mortar which incorporates the most advanced cement chemistry, microsilica, fibre and styrene acrylic copolymer technology. This results in a rapid hardening, normal 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 requiring only the addition of clean water.


  • Incorporates the latest proven cement chemistry, microsilica, fibre and styrene acrylic copolymer technology
  • Pre-packaged material requiring mixing with clean water to give an easily trowellable mortar with maximum application thickness of 80mm in vertical, overhead and horizontal 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
  • Resistant to sulphates to class DS-5/5m of BRE Special Digest 1
  • Improved tensile and abrasion resistance. Excellent low sag properties
  • 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. Compliant with LU Standard 1-085 ‘Fire Safety Performance of Materials’.

Specification Clause

The repair mortar shall be a single component cementitious mortar, incorporating microsilica, fibre and styrene acrylic copolymer technology, and shall be CE marked in accordance with BS EN 1504-3 Class R4. It shall be BBA Certified and comply with the following performance specification:

  • 5-80mm application thickness in a single layer even overhead
  • Compressive strength at 20°C of at least 33 MPa in 1 day and 56.5 MPa in 28 days
  • Flexural strength at 28 days (28°C & 65% R.H) of at least 5.1 MPa in accordance with BS 4551
  • Resistant to sulphates to class DS-5/5m of BRE Special Digest 1.
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