deficiency should be determined. Because many deficiencies
are caused by more than one mechanism, a basic understanding
of the causes of concrete deterioration is essential to
determine what has actually happened to a particular concrete
structure and why. Only after the evaluation is complete can a
suitable remedial action plan be developed, repair materials
selected, and drawings and specifications prepared.
1.3.3 Selecting repair methods and materials—After the
cause or causes of the damage or deterioration have been
determined, appropriate repair materials and methods can be
selected considering the following recommendations.
1.3.3.1—The engineer can incorporate adjustments or
required modifications to remedy the cause of the deterioration,
such as changing the water drainage pattern, eliminating
sources of cavitation damage, providing for differential
movements, or eliminating exposure to deleterious substances.
The engineer should have a thorough understanding of factors
affecting the durability of concrete and the causes of different
types of cracking (ACI 201.2R, ACI 222R, and ACI 224.1R).
It is not always possible to correct causes of deterioration; for
example, it may not be possible to change the environment
with which the concrete is exposed. In such cases, every
reasonable effort should be made to mitigate the problem.
1.3.3.2—The engineer should consider outside constraints,
such as limited access to the structure; the operating schedule
of the structure; any limitations imposed by the owner of the
structure, including the cost; the required useful life of the
repaired structure; and the weather implications.
or construction. Only after the cause or causes of deficiency
are determined can rational decisions be made regarding the
selection of a proper repair system and the implementation
of the repair process (Fig. 1.1).
1.3.3.3—Inherent problems that cannot be corrected,
such as continued exposure to chlorides in deicing salts or
salt water and continued exposure to deleterious chemicals,
should also be considered. In these cases, the repair and
protection system extends the life of the structure but does
not eliminate the causes of deterioration.
1.3.3.4—On some projects, environmental and occupational
safety requirements may have a major impact on the
selection of materials, methods, or both. Airborne vapor or
particles that might result from the use of certain
membranes, sealers, and coatings, and from abrasive blasting
of silica aggregate contained in concrete is a significant
concern. Noise and hazardous waste may be considerations
as well. Environmental and occupational safety constraints
are governed by specific requirements and policies of
owners; the Environmental Protection Agency (EPA); the
Occupational, Safety, and Heath Administration (OSHA);
and local regulations.
1.3.3.5—The engineer should be aware of advantages and
disadvantages of making permanent versus temporary repairs,
and select the materials and methods that match the intended
life of the repaired structure. Occasionally, there may be
situations where it is more appropriate to address the
symptoms and not the causes of the problem; for example, it
may be more cost effective to temporarily shore the structure.
1.3.3.6—Structural safety before, during, and after the
repair should be considered. Repair work often involves the
removal of concrete and reinforcing steel that reduces the shear, bending, tensile, and compression capacities, or
stability of the structure. Structural analysis, if necessary,
should be performed for live and dead loads and the effects of
volume changes resulting from temperature changes. Areas of
special concern include negative moment areas in slabs and
beams, cantilever beams, joint and connection details, precast
spandrel beams, columns, and live loads imposed by repair
equipment and material storage. Also, any requirements for
temporary supports, shoring, and strengthening should be
determined.