In its simplest form, concrete is a mixture of paste and aggregates, or rocks. The paste,

composed of Portland cement and water, coats the surface of the fine (small) and coarse
(larger) aggregates. Through a chemical reaction called hydration, the paste hardens and
gains strength to form the rock-like mass known as concrete.
Within this process lies the key to a remarkable trait of concrete: it’s plastic and malleable
when newly mixed, strong and durable when hardened. These qualities explain why one
material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses
and dams.
Concrete is easy to work with, versatile, durable, and economical. By observing a few
basic precautions, it is also safe-one of the safest building materials known.

Outlined below are some simple suggestions for protection, prevention and repair of
common concrete and masonry related distress.

Rehabilitation and Retrofitting

Why Does Concrete Need Repairing?
• Corrosion of reinforcement
• Insufficient reinforcement
• Chemical damage
• Excessive loads
• Structural damage
• Fire damage
• Seismic damage
• Blast damage

Factors to Decide Rehabilitation and Retrofitting
• Likely service life
• Repair methods
• Repair materials

Repair options
• Grouting and crack repairs
• Patch repair
• Replacement of structurally weak concrete
• Replacement of delaminated concrete
• Replacement of corroded steel reinforcement
• Cleaning and passivating reinforcement
• Concrete and corrosion protection (Jacketing)