The Key Stages in the Process of Corrosion Management
The successful repair and protection of concrete structures which have been damaged or which have deteriorated requires professional assessment, then design, supervision and execution of technically correct principals – according to the forthcoming European Standard being developed by EN 1504.
This article is intended to give guidance on the correct procedure and on the appropriate products and systems for the selected strategy. The key stages in the process are:
1. Assessment Survey of the Condition of the Structure
The assessment of the condition of a damaged or deteriorated reinforced concrete structure should only be made by qualified and experienced people. The process of assessment will always include the following aspects: The current condition of the structure including visible, non-visible and potential defects.Review of the past, current and future exposure.
2. Diagnosis of the Cause of Deterioration
Following review of the original design, construction methods and programme, and the assessment survey, identify the “root causes” of damage: Identify mechanical, chemical and physical damage to the concrete. Identify concrete damage due to reinforcement corrosion.
3. Determine the Repair and Protection Objectives
With most damaged or deteriorated structures the owner has a number of options which will effectively decide the appropriate repair and protection strategy to meet the future requirements of the structure. The options include:
- Do nothing.
- Downgrade the structure or its capacity.
- Prevent or reduce further damage without repair.
- Improve, refurbish or strengthen all or part of the structure.
4. Select the appropriate Repair and Protection Strategy
It is necessary to clarify the owner’s requirements and instructions in relation to:
- The required durability, requirements and performance.Intended design life.
- How loads will be carried before, during and after the repair.
- The possibility for future repair works including access and maintenance.
- Costs of the alternative solutions.
- The consequences and likelihood of structural failure.
- The consequences and likelihood of partial failure (falling concrete, water
- ingress, etc).
- The need for protection from sun, rain,frost, wind, salt and/or other pollutants
- during the works.
- The environmental impact or restrictions on the works in progress, particularly the noise and the time taken to carry out the work.
- The likely environmental/aesthetic impact of the improved/reduced appearance of alternative solutions.
5. Definition of the future Maintenance Requirements and Procedures
What is the mode and result of the selected materials deterioration, i.e. chalking, embrittlement, discolouration, delamination? What surface preparation and access systems will eventually be required and when? Who is responsible and how will it be financed?