Basis of Concrete Repair & Corrosion Control

Upen Patel, Marketing Manager, BASF Construction Chemicals (India) Pvt. Limited, Mumbai.

Background

Once concrete repairs and strengthening was considered as an activity of rejuvenating the old structures and making them capable of bearing loadings and environmental stresses in the future life. Today we are constructing more advanced and ever more-demanding structures with complex detailing. In case proper steps are not taken on quality control and proper supervision the concrete repairs and strengthening may start during the construction stage itself. Reduced emphasis on adequate quality assurance results in to construction errors and creates needs for repairs and strengthening during or after construction. With the complex performance demands of the new structures and ever longer life expectancies makes concrete repairs, strengthening and protection procedures more and more demanding. This article is an attempt to present the fundamentals of concrete repairs and strengthening in a step-by-step process and it focuses on the advantages and disadvantages of current practices and provides an insight in the futuristic, but more simple to adopt techniques.

Basic Definitions

• Repairs: To replace or correct deteriorated, damaged or faulty materials, components, or elements of a concrete structure.
• Strengthening: The process of restoring the capacity of weakened components or elements to their original design capacity, or increasing the strength of a concrete structure.
• Protection: Making the structure able to resist the likely deterioration due to the surroundings/environment.

Why does Concrete need Repairs?

There are many factors which lead to the need of repairs such as:

• Corrosion of reinforcement due to carbonation, chlorides
• Effects of Sulphates
• Alkali silica reaction
• Environmental pollution
• Deicing salts
• Acid rains
• Oils
• Freeze thaw cycles
• Abrasion or erosion from wind or water borne agents
• Plants or micro organisms
• Overloading
• Physical settlement
• Impact
• Earthquake
• Fire
• Chemical attack by aggressive chemicals, in industrial or marine environment sewerage or even soft water.