Civil Engineering Reference
In-Depth Information
compare submitted tenders and value additional works. In the 1990s there
was a move towards developing bill items for concrete repair using volume
measurement in litres but this created its own problems as the repairs were
often wrongly quantified.
Today we have the Concrete Repair Association Method of Measurement
which is the acknowledged standard for quantifying the concrete repairs.
This is a schedule of repair sizes for overhead, wall and floor repairs. The
schedule has been used in the UK since 2000 and has proved to be very
successful.
The quantification of the work required should come from a desk-top
study of the available drawings and the on-site inspection and investigation
work. If a close inspection of all the exposed concrete is not possible then a
sample section should be used then pro rata for the full area. It is important
to add an additional percentage for contingency which may be 10-30%.
This additional quantity is based on the experience and confidence of the
Surveyor. The CRA Method of Measurement will enable a comparison of
tenders and form the basis for the measurement of works during contract
execution.
12.4 Specification
The repair specifications for concrete repair are usually based on a
particular material supplier who should be a member of the Concrete Repair
Association (CRA) with reference to 'or similar approved', or a member of
an appropriate similar organisation in other countries.
The recent introduction of the European Standard for concrete repair
BS EN 1504, entitled 'Products and systems for the repair and protection
of concrete structures', is now only just starting to make an impact on
specifications. This standard is mandatory for government-funded projects
and will undoubtedly be adopted by the whole industry.
BS EN 1504 covers the whole concrete repair process, from the initial
identification of a problem, through to the works on site. It requires that a
'whole-life cost' approach is taken so that the anticipated future needs of the
client are met.
The standard consists of 10 parts, each covered by a separate document.
It will give the structure owner an increased level of confidence as, for the
first time, all issues of concrete repair and protection are addressed by a
single integrated European standard.
For further information, the Concrete Society has published a guidance
note, Technical Report TR69, to guide consultants and contractors through
the application of BS EN 1504.
Chapter 11
also details how BS EN 1504
was adopted and how the various parts work.
Material suppliers are providing specifications and products which are
compliant with the standard but care must be taken to ensure that the correct
specification is selected for the application.
