Surface Protection System – Protection against Ingress (EN1504-2, DWI 31, BBA, WRAS)


Cementitious Coating 851 is designed for internal and external structural waterproofing of concrete and other mineral substrates. Cementitious Coating 851 resists positive and negative pressure under 100m head in water retaining and below ground structures as well as roofs and decks. It provides chloride protection on highway and coastal structures and enhances the durability of reinforced concrete by reinstating effective cover to achieve the specified design life.

Cementitious Coating 851 is a two component, thixotropic, cementitious modified polymer coating with high adhesion to both concrete and steel. Cementitious Coating 851 forms a hard, highly alkaline coating with a degree of elasticity which not only protects the concrete, or other substrates, from the effects of aggressive acid gases, moisture and chlorides, but also has greatly enhanced chemical resistance. It is
particularly suited for the protection of concrete in sulphate contaminated ground conditions. Can be reinforced with Cemprotec 2000-S tape to accommodate movement around details and
over cracks and joints where further movement is expected.

Anti-Chloride Protection Coating Still Going Strong After 30 Years


  • Incorporates the latest proven cement chemistry, microsilica, fibre and styrene acrylic copolymer technology.
  • Brush, trowel or spray applied normally in two coats. Floors and decks are a one coat application.
  • Pre-packaged material only require mixing on site.
  • Excellent adhesion to sound prepared concrete substrates and steel.
  • Dense matrix offers low permeability to water, even at 10 bar positive and negative pressure, and very high diffusion resistance to carbon dioxide gas and chloride ions.
  • Provides the equivalent to 100mm of good quality concrete cover.
  • Non-toxic when cured and is listed as authorised under Regulation 31 for use in the supply of drinking water.
  • Easily overcoated with Flexcrete’s specialist membranes to provide further protection and aesthetic quality.


CE marked in accordance with BS EN 1504 Part 2. Approved by the BBA, Certificate No. 05/4276. Listed under DWI Regulation 31 for drinking water applications. Compliant with LU Standard 1-085 ‘Fire Safety Performance of Materials’.

Specification Clause

The structural waterproofing coating shall be a two-component, thixotropic, polymer modified cementitious coating. It shall be CE marked in accordance with BS EN 1504-2, and shall comply with the following performance specification:

  • Impermeable to water under 10 bar hydrostatic pressure such that a 2.0mm coating is equivalent to 1000mm of concrete
  • Carbon dioxide gas diffusion resistance coefficient of at least 2,600,000 in accordance with the Taywood Test, such that the equivalent air layer thickness at 2.0mm coating is 5,200m.
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