Civil Engineering Reference
In-Depth Information
perspective
John Drewett
12.1 Introduction
The concrete repair industry has come a long way since 1954 when Concrete
Repairs Ltd (CRL) was established as a contractor. Until the early 1980s
the majority of repairs were to buildings and marine structures. The work
consisted of breakout using hand pneumatic tools and reinstatement using
site batched repair mortars and concretes with waterproof additives, such as
styrene butadiene rubber (SBR) polymers, to enhance durability.
In the 1980s pre-bagged repair materials using freeze-dried polymers
started to become available which improved the quality control for the
repairs, and complete repair systems were marketed by suppliers. These
consisted of steel and concrete primers, repair concretes and mortars, and
finish coating systems.
For the first time clients could specify with some confidence a complete
repair system from one supplier. But specifiers were still struggling to
quantify the works in this growing industry due to lack of experience and no
acknowledged method of measurement. It was very common for concrete
repair projects to go way over budget due to poorly constructed bills of
quantities and underestimates in quantifying the work.
The market for concrete repair in the UK has grown in the last 20 years
as the concrete structures of the 1950s and 60s have matured and it was
realised that chlorides from de-icing salts and admixtures such as calcium
chloride have initiated rapid corrosion of the reinforcement.
There has been a great deal of research into concrete deterioration and in
particular corrosion of the reinforcement. This has led to the development
of corrosion control techniques and improved repair systems which have
brought about a step change in the way we deal with concrete repair and
produced harmonised European Standards.
This chapter will look at how concrete repair is quantified, specified,
procured and executed but first of all it will address the importance of safety.
