Concrete Surface |
The
impermeability and appearance requirements for concrete surfaces vary widely.
Detailed planning and execution of the structure are required to meet these
requirements.
Maximum
surface impermeability is essential for all durability requirements. The attack
always comes from outside to inside. Over vibration or inadequate curing
weakens these zones. High quality appearance requirements have led to the
production of so-called “fair-faced” concrete.
Appearance
of concrete surfaces
In modern architecture
concrete is increasingly used as a design feature as well as for its mechanical
properties. This means higher specifications for the finish (exposed surfaces).
There are many ways to produce special effects on these exposed surfaces:
·
Select a suitable concrete mix
·
Specify the formwork material and type (the
formwork must be absolutely impervious!)
·
Use the right quantity of a suitable release
agent
·
Select a suitable placement method
·
Use form liners if necessary
·
Consider any necessary retouching
·
Color using pigments
·
Install correctly (compaction, placing etc.)
·
Thorough curing in addition to all of these
factors listed, the following are important for the concrete mix:
Exposed
aggregate concrete
Exposed
aggregate concrete is a popular surface design feature, e.g. for retaining
walls, façade panels, garden features etc.
The
aggregate structure is exposed on the surface by washing off and out. This
requires surface retardation, which must be effective down to several mm.
In correctly
designed exposed aggregate concrete, 2/3 of any single coarse aggregate is
still within the hardened cement matrix.