Civil Engineering Reference
In-Depth Information
Further details are given in
Table 17.2.
These materials mainly involve keeping aggressive materials and chemicals
out of concrete. Basically there are pore liners (H) that repel water (e.g.
silane and siloxane), pore blockers (I) that soak into the surface and seal the
porosity (e.g. resins) and conventional coatings (C) that adhere to the surface
of the concrete.
Within BS EN 1504 Part 2 there are a large number of Standards that are
used to characterise the coating system, many of which also govern factory
control systems - ensuring that products are manufactured consistently.
These are termed identification requirements (the material complies with its
description) and performance requirements (the material performs according
to the claims made for it). The manufacturer's quality control regime aims
to test a representative number of samples for compliance. These tests are,
Principle no. and definition
Methods based on the principle
1. Protection against ingress
Reducing/preventing the ingress of adverse
agents.
Pore-blocking impregnation
*
Surface coating with or without
the ability to accommodate crack
formation and movement
2. Moisture control
Adjusting and maintaining the moisture
content in the concrete within a specified
range of values.
Hydrophobic impregnation
*
Surface coating
3. Concrete restoration
-
4. Structural strengthening
-
5. Physical resistance
Increasing resistance to physical/
mechanical attack.
Overlays or coatings
Pore-blocking impregnation
6. Resistance to chemicals
Increasing resistance of the concrete
surface to deterioration by chemical attack.
Overlays or coatings
Pore-blocking impregnation
7. Preserving or restoring passivity
-
8. Increasing resistivity
Increasing the electrical resistivity of the
concrete.
Limiting moisture content by
surface treatments or coatings
9. Cathodic control
Creating conditions in which potentially
cathodic areas of reinforcement are unable
to drive an anodic reaction.
Limiting oxygen content (at the
cathode) by saturation or surface
coating
10. Cathodic protection -
11. Control of anodic areas -
*
The distinction between pore-blocking and hydrophobic impregnation is discussed in Section
17.4.
