Structural Repair
Successful
Concrete
Repair
Preparation, cleaning and breaking
out of the deteriorated concrete
Thorough testing of the
affected area is vital
Before awarding a concrete repair project, all
involved should understand the mechanisms
for failure of concrete as well as the repair
techniques available, says the Structural
Concrete Alliance.
Concrete is an extremely successful construction
material that is versatile, relatively low in cost and
readily available. However, with many of the UK’s
existing concrete structures dating from the 1960’s and
70’s, a number of them are now showing significant
signs of deterioration and are in need of repair.
To assist consultants, authorities, surveyors and
engineers with responsibility for awarding maintenance
and refurbishment contracts, the Structural Concrete
Alliance offers a range of guidance, presentations
and seminars, which provide important advice on
mechanisms for failure, methods of concrete repair and
contractor selection.
The Concrete Repair Association’s popular CPD
presentation, The Route to Successful Concrete
Repair, provides an essential introduction to concrete
repair, emphasising overall considerations to be taken
into account when undertaking a project and providing
a very useful guideline to the best approach to be
adopted.
The presentation, which can be delivered to clients
on site at a time to suit, introduces the mechanisms
for failure associated with concrete; the methods for
diagnosis of the problem, as well as repair techniques.
CONCRETE REPAIR CONSIDERATIONS
Before any repair is undertaken, it is important that
a thorough investigation of the nature and extent of
the damage is carried out so that the causes, as well
as the symptoms, can be treated. In most cases,
the underlying causes of a problem will be due to
degradation of the concrete matrix or corrosion of the
reinforcement.
Visual inspection of the damage is insufficient and
more thorough testing will be required. Testing
procedures include: visual survey, hammer testing,
chloride testing reinforcement cover assessment,
half-cell potential surveys, or carbonation testing using
phenolphthalein to test the penetration of carbonation.
Once the cause of the damage and the client’s
requirements for the site are understood, a
specification for the repair work can be developed.
Material appropriate to the repair must be selected,
based on required performance and project
characteristics, so the choice of repair method and
material requires specialist knowledge and experience.
Before any specification can
be made, an evaluation of the
products that could be used and
careful assessment of possible
contractors is necessary. Due
consideration should be given
to manufacturer and contractor
track records. Industry and third
party accreditations to BS EN 9001 and BS EN 14001,
CHAS, Construction, Exor, etc, should be demanded,
together with manufacturer recommendations
and approvals, third party references and similar
considerations.
The repair process also involves several stages. Firstly,
and extremely important, is preparation, cleaning and
breaking out of the deteriorated concrete. For items
that are of structural importance such as load bearing
elements, advice must be sought from a structural
engineer. Steel reinforcement must be cleaned and
protected appropriately before the area is primed and
reinstated.
The choice of repair techniques is also important.
There are several methods, ranging from hand
applied, spray applied, or flowable mortars, grouts, or
concretes. Fairing coats can be used to give repaired
areas a clean, smooth and uniform surface, whilst
protective coatings provide protection, increased
resistance to future deterioration and offer an attractive
finish.
Maintenance of the structure post repair is another
essential element of the overall rehabilitation process,
to ensure that repaired areas perform to specification
and achieve the necessary residual service life.
All repairs should be carried out in accordance with
the requirements of BS EN 1504, which addresses
all stages of the repair process. However, though
it provides a framework, BS EN 1504 does not
guarantee a successful repair, since only a qualified
and experienced professional can ensure the right
material has been selected and that it has been applied
properly.
GETTING IT RIGHT FIRST TIME
While various builders and contractors may claim to
be able to conduct concrete repairs, those involved
in the maintenance and refurbishment of reinforced
concrete must be aware that, unless contractors have
the necessary specialist knowledge and experience,
it is unlikely that repairs carried out will be safe, fit for
purpose and durable.
STRUCTURAL CONCRETE ALLIANCE TEL: 01420 471614
Repair techniques range from
hand or spray applied flowable
mortars, grouts, or concretes
This is where selecting a member of one of the
associations that make up the Structural Concrete
Alliance can help to ensure that repairs are completed
properly, are fit for purpose and appropriate to the
service life expectations for the building or structure.
The Structural Concrete Alliance is an umbrella
organisation which brings together the Concrete Repair
Association (CRA), Corrosion Prevention Association
(CPA) and Sprayed Concrete Association (SCA) to
provide a single co-ordinated voice for the structural
concrete refurbishment and repair industry.
For concrete repairs, members of the Concrete Repair
Association offer independent advice, technical
expertise and exceptional service. All CRA members
are BS EN ISO 90001 and BS EN ISO 14001
accredited; can demonstrate a proven track record and
capability; and comply with the CRA’s stringent code of
practice. This is why many clients specify membership
of the CRA as a requirement in tenders involving
concrete repair.
WWW.STRUCTURALCONCRETEALLIANCE.ORG.UK
READER ENQUIRY NO: 16
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